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Effect of restricted pacifier use in breastfeeding term infants for increasing duration of breastfeeding

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Authors

Sharifah Halimah Jaafar1, Shayesteh Jahanfar2, Mubashir Angolkar3, Jacqueline J Ho4

Background - Methods - Results - Characteristics of Included Studies - References - Data Tables & Graphs


1Department of Obstetrics and Gynaecology, KPJ Ipoh Specialist Hospital, Ipoh, Malaysia [top]
2Department of Public Health, School of Population and Public Health, University of British Columbia, Vancouver, Canada [top]
3Women's and Children's Health Research, JN Medical College, Belgaum, India [top]
4Department of Paediatrics, Penang Medical College, Penang, Malaysia [top]

Citation example: Jaafar SH, Jahanfar S, Angolkar M, Ho JJ. Effect of restricted pacifier use in breastfeeding term infants for increasing duration of breastfeeding. Cochrane Database of Systematic Reviews 2012, Issue 7. Art. No.: CD007202. DOI: 10.1002/14651858.CD007202.pub3.

This is a Cochrane Pregnancy and Childbirth Group External Web Site Policy systematic review.

Contact person

Sharifah Halimah Jaafar

Department of Obstetrics and Gynaecology
KPJ Ipoh Specialist Hospital
Raja Dihilir Street
30450 Ipoh
Perak
Malaysia

E-mail: drshj65@gmail.com
E-mail 2: drsharifah65@gmail.com

Dates

Assessed as Up-to-date: 21 May 2012
Date of Search: 14 March 2012
Next Stage Expected: 31 May 2013
Protocol First Published: Issue 3, 2008
Review First Published: Issue 3, 2011
Last Citation Issue: Issue 7, 2012

What's new

Date / Event Description
01 May 2012
Feedback incorporated

Authors' response to feedback from Di Mario added (see Feedback 1); and feedback from Paulussen and authors' response added (see Feedback 2).

01 May 2012
New citation: conclusions not changed

Review updated and title changed from "Pacifier use versus no pacifier use in breastfeeding term infants for increasing duration of breastfeeding" to "Effect of restricted pacifier use on breastfeeding duration", as detailed in the authors' response to feedback - see Feedback 1.

14 March 2012
Updated

Search updated. No new trial reports identified.

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History

Date / Event Description
22 December 2011
Feedback incorporated

Comments from Simona Di Mario, Adriano Cattaneo, Vittorio Basevi and Nicola Magrini added - see Feedback.

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Abstract

Background

To successfully initiate and maintain breastfeeding for a longer duration, the World Health Organization's Ten Steps to Successful Breastfeeding recommends total avoidance of artificial teats or pacifiers for breastfeeding infants. Offering the pacifier instead of the breast to calm the infant may lead to less frequent episodes of breastfeeding and as a consequence may reduce breast milk production and shorten duration of breastfeeding; however, this remains unclear.

Objectives

To assess the effect of unrestricted versus restricted pacifier use in healthy full-term newborns whose mothers have initiated breastfeeding and intend to exclusively breastfeed, on the duration of breastfeeding, other breastfeeding outcomes and infant health.

Search methods

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (14 March 2012).

Selection criteria

Randomised and quasi-randomised controlled trials comparing unrestricted versus restricted pacifier use in healthy full-term newborns who have initiated breastfeeding regardless of whether they were born at home or in the hospital.

Data collection and analysis

Two authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data were checked for accuracy.

Main results

We found three trials (involving 1915 babies) for inclusion in the review but have included only two trials (involving 1302 healthy full-term breastfeeding infants) in the analysis. Meta-analysis of the two combined studies showed that pacifier use in healthy breastfeeding infants had no significant effect on the proportion of infants exclusively breastfed at three months (risk ratio (RR) 0.99; 95% confidence interval (CI) 0.93 to 1.05), and at four months of age (RR 0.99; 95% CI 0.92 to 1.06) and also had no effect on the proportion of infants partially breastfed at three months (RR 1.00; 95% CI 0.98 to 1.13), and at 4 months of age (RR 1.01; 95% CI 0.98 to 1.03).

Authors' conclusions

Pacifier use in healthy term breastfeeding infants, started from birth or after lactation is established, did not significantly affect the prevalence or duration of exclusive and partial breastfeeding up to four months of age. However, evidence to assess the short-term breastfeeding difficulties faced by mothers and long-term effect of pacifiers on infants' health is lacking.

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Plain language summary

Effect of pacifier use on duration of breastfeeding in full-term infants

 

Breast milk is superior to other baby foods in providing balanced nutrition and protection against allergy and infection to newborns. Breastfeeding is recommended by the World Health Organization, exclusively in the first six months and then as a dietary supplement. Breastmilk production and supply are maintained by frequent suckling of the breast and nipple stimulation. A pacifier is a non-nutritive sucking device used to calm an infant that has become a cultural norm in many parts of the world. However there is a widespread belief that pacifiers may interfere with breast milk production and lead to discontinuation of breastfeeding.

Our review concluded that for mothers who are motivated to breastfeed their infants, pacifier use before or after breastfeeding was established did not significantly affect the prevalence or duration of exclusive and partial breastfeeding up to four months of age. The review provided moderate evidence from three randomised controlled trials (involving 1915 babies) comparing unrestricted with restricted pacifier use by healthy, full-term breastfeeding infants; two of the trials (1302 babies) were included in the analysis. However, there is a widespread belief that pacifiers may interfere with breast milk production and lead to discontinuation of breastfeeding.

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Background

The superiority of breast milk in providing balanced nutrition, protection against allergy and infection in newborns is well documented (Chandra 1979; Oddy 2001). Thus, the World Health Organization (WHO) Expert Consultation recommends that infants be exclusively breastfed (infant receives only breast milk with no other liquids including water or solids) up to the first six months of life and as a dietary supplement thereafter. In order to successfully initiate and maintain breastfeeding for longer duration, and avoid supplementary feeding, the WHO's Ten Steps to Successful Breastfeeding recommends artificial teats or pacifiers should not be given for breastfeeding infants. The use of a pacifier, a non-nutritive sucking device to calm an infant, is relatively widespread and has become a cultural norm in many parts of the world (Barros 1995). Pacifiers are often believed to be harmless or even necessary and beneficial for infants' development (Victora 1997). However, the use of pacifiers for breastfeeding infants remain controversial.

Breastmilk production and supply are maintained by frequent suckling of the breast and nipple stimulation (Aarts 1999; Neville 1988). In order to breastfeed successfully, infants must learn to attach and suckle properly at the breast during the first few days of life. Effective breast sucking technique requires the infant to have a wide open mouth, with the tongue under the areola. Expression of milk from the breast is by slow and deep sucks, while sucking on a pacifier is basically superficial sucking (Righard 1992) where the infant is sucking on a teat with short and fast sucks using minimal effort. The mechanical differences between sucking at the breast and sucking on a pacifier may result in 'nipple confusion' (Gomes 2006; Neifert 1995), incorrect latching onto the breasts and superficial sucking on the mother's nipples (Righard 1998). Improper technique of sucking on the breasts may lead to cracked nipples and mastitis, which may further impede breastfeeding. Evidence from a cohort study reported that breastfeeding difficulties during the first week of postpartum were significantly associated with termination of breastfeeding by week 10 of life (Scott 2005). There are beliefs, based on observational evidence, that early exposure of infants to the pacifier is associated with cessation of exclusive breastfeeding by three to six months (Mascarenhas 2006; Scott 2005), and overall breastfeeding by 12 months (Scott 2005). Offering the pacifier instead of the breast to calm the infant may lead to less frequent episodes of breastfeeding. This in turn may reduce breast milk production and shorten duration of breastfeeding in the long term (Howard 1999). Furthermore, infants may get used to the pacifier, and develop a preference for an artificial teat instead of the mother's nipple.

On the other hand, it remains unclear whether breastfeeding cessation and a maternal intention to wean the infant from exclusive breastfeeding precedes the use of a pacifier or vice versa. It is possible that a mother may have experienced breastfeeding difficulties early and intended to stop breastfeeding, by introducing the pacifier to the infant in preparation to take on bottle feeding. Interestingly, evidence also shows that pacifiers can have a positive effect on breastfeeding, as they may help to take the infant off the breast and thereby increase the interval between feedings and possibly breast milk intake by the infant (Victora 1997). Observational evidence also indicates that occasional use of the pacifier has no effect on breastfeeding duration compared to daily pacifier use (Ullah 2003; Vogel 2001) and thus it remains unclear whether pacifiers are an independent causal factor for reducing breastfeeding duration. In addition, the use of pacifiers might be protective against sudden infant death syndrome (Mitchell 2006; Saririan 2006), although its mechanism is unknown. However, prolonged non-nutritive sucking on the pacifier is associated with an increased risk of recurrent acute otitis media (Jackson 1999), oral candidiasis (Darwazeh 1995) and dental malocclusion (Caglar 2005).

Pacifier use is a life style choice so it is not possible to assign mothers randomly to pacifier versus no pacifier use. Therefore, to answer this question, studies could assign mother-infant pairs to unrestricted compared with restricted pacifier use.

Therefore, the aim of this review is to study the effect of restricted pacifier exposure in healthy infants whose mothers have initiated breastfeeding and intend to exclusively breastfeed, on the duration of breastfeeding and infant health.

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Objectives

To assess the effect of unrestricted versus restricted pacifier use in healthy full-term newborns whose mothers have initiated breastfeeding and intend to exclusively breastfeed, on the duration of breastfeeding, other breastfeeding outcomes and infant health.

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Methods

Criteria for considering studies for this review

Types of studies

All randomised controlled trials including quasi-randomised trials.

Types of participants

Healthy full-term newborns whose mothers have initiated breastfeeding and intend to exclusively breastfeed regardless of whether they were born at home or in hospital. We will exclude studies including newborns exposed to bottle feeding prior to enrolment.

Types of interventions

Unrestricted or actively encouraged use of a pacifier compared with advice against pacifier use. We excluded studies evaluating occasional pacifier use to provide procedural pain relief.

Types of outcome measures

Definition of breastfeeding and partial breastfeeding

Full or exclusive breastfeeding is defined as no food (solid or liquid including water) other than breast milk. Almost exclusive breastfeeding allows infrequent supplemental liquids, other than milk formula, and in partial breastfeeding other milk supplements are regularly given along with breastfeeding (Labbok 1990).

Primary outcomes

Duration of breastfeeding as measured by one of the following:

  1. mean duration of full breastfeeding (months) as defined by Labbok 1990;
  2. mean duration of any or partial breastfeeding (months);
  3. prevalence or proportion of infants being fully or partially breastfed at three, four and six months of age.
Secondary outcomes
  1. Rate of breastfeeding difficulties (cracked nipples, breast engorgement, mastitis).
  2. Maternal satisfaction and level of confidence in parenting.
  3. Mean episode/frequency of infant crying and fussing per day .
  4. Infants' health: incidence of sudden infant death syndrome, oral candidiasis, otitis media and dental malocclusion.

Search methods for identification of studies

Electronic searches

We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register by contacting the Trials Search Co-ordinator (14 March 2012). 

The Cochrane Pregnancy and Childbirth Group’s Trials Register is maintained by the Trials Search Co-ordinator and contains trials identified from: 

  1. quarterly searches of the Cochrane Central Register of Controlled Trials (CENTRAL);
  2. weekly searches of MEDLINE;
  3. handsearches of 30 journals and the proceedings of major conferences;
  4. weekly current awareness alerts for a further 44 journals plus monthly BioMed Central email alerts.

Details of the search strategies for CENTRAL and MEDLINE, the list of handsearched journals and conference proceedings, and the list of journals reviewed via the current awareness service can be found in the ‘Specialized Register’ section within the editorial information about the Cochrane Pregnancy and Childbirth Group External Web Site Policy

Trials identified through the searching activities described above were each assigned to a review topic (or topics). The Trials Search Co-ordinator searched the register for each review using the topic list rather than keywords. 

We did not apply any language restrictions.

Data collection and analysis

Three review authors independently assessed for inclusion all the potential studies identified as a result of the search strategy. We resolved any disagreement through discussion.

Selection of studies

Three review authors independently assessed for inclusion all the potential studies identified as a result of the search strategy. We resolved any disagreement through discussion.

Data extraction and management

We designed a form to extract data. For eligible studies, at least two review authors extracted the data using the agreed form. We resolved discrepancies through discussion. We entered data into Review Manager software (Higgins 2009) and checked it for accuracy.

When information regarding any of the above was unclear, we contacted authors of the original reports to provide further details.

Assessment of risk of bias in included studies

Two review authors independently assessed risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2009). We resolved any disagreement by discussion.

(1) Sequence generation (checking for possible selection bias)

We described for each included study the method used to generate the allocation sequence in sufficient detail to allow an assessment of whether it produced comparable groups.

We assessed the methods as:

  • adequate (any truly random process, e.g. random number table; computer random number generator);
  • inadequate (any non-random process, e.g. odd or even date of birth; hospital or clinic record number); or
  • unclear.   
 (2) Allocation concealment (checking for possible selection bias)

We described for each included study the method used to conceal the allocation sequence and determined whether intervention allocation was foreseen in advance of, or during recruitment, or changed after assignment.

We assessed the methods as:

  • adequate (e.g. telephone or central randomisation; consecutively numbered sealed opaque envelopes);
  • inadequate (open random allocation; unsealed or non-opaque envelopes, alternation; date of birth);
  • unclear.   
(3) Blinding (checking for possible performance bias)

We described for each included study the methods used, if any, to blind study participants and personnel from knowledge of which intervention a participant received. We considered that studies were at low risk of bias if they were blinded, or if we judged that the lack of blinding could have affected the results. We assessed blinding separately for different outcomes or classes of outcomes.

We assessed the methods as:

  • adequate, inadequate or unclear for participants;
  • adequate, inadequate or unclear for personnel;
  • adequate, inadequate or unclear for outcome assessors.
(4) Incomplete outcome data (checking for possible attrition bias through withdrawals, dropouts, protocol deviations)

We described for each included study, and for each outcome or class of outcomes, the completeness of data including attrition and exclusions from the analysis. We stated whether attrition and exclusions were reported, the numbers included in the analysis at each stage (compared with the total randomised participants), reasons for attrition or exclusion where reported, and whether missing data were balanced across groups or were related to outcomes. Where sufficient information was reported, or was supplied by the trial authors, we re-included missing data. We assessed methods as:

  • adequate;
  • inadequate;
  • unclear.

We would not include studies for analysis if:

(A) more than 20% of participants excluded;

(B) more than 20% of analysis not in randomisation groups and not possible to restore participants to correct group.

(5) Selective reporting bias

We described for each included study how we investigated the possibility of selective outcome reporting bias and what we found.

We assessed the methods as:

  • adequate (where it was clear that all of the study’s pre-specified outcomes and all expected outcomes of interest to the review had been reported);
  • inadequate (where not all the study’s pre-specified outcomes had been reported; one or more reported primary outcomes were not pre-specified; outcomes of interest were reported incompletely and so could not be used; study failed to include results of a key outcome that was expected to have been reported);
  • unclear.
(6) Other sources of bias

We described for each included study any important concerns we had about other possible sources of bias.

We assessed whether each study was free of other problems that could put it at risk of bias:

  • yes;
  • no;
  • unclear.
(7) Overall risk of bias

We made explicit judgements about whether studies were at high risk of bias, according to the criteria given in the Handbook (Higgins 2009). With reference to (1) to (6) above, we assessed the likely magnitude and direction of the bias and whether we considered it was likely to impact on the findings.  We explored the impact of the level of bias through undertaking sensitivity analyses - see Sensitivity analysis

Measures of treatment effect

Dichotomous data

For dichotomous data, we presented results as summary relative risk with 95% confidence intervals.

Continuous data

For continuous data, we used the mean difference if outcomes were measured in the same way between trials. If we had found trials that measured the same outcome but used different methods we planned to use the standardised mean difference to combine trials. If there was evidence of skewness, this was reported.

Unit of analysis issues

Cluster-randomised trials

We did not identify any cluster-randomised trials for inclusion. In future updates of this review, if we identify cluster-randomised trials for inclusion they will be included in the analyses along with individually randomised trials. We will adjust their sample sizes or standard errors using the methods described in the Handbook (Higgins 2009) using an estimate of the intracluster correlation co-efficient (ICC) derived from the trial (if possible), from a similar trial or from a study of a similar population. If we use ICCs from other sources, we will report this and conduct sensitivity analyses to investigate the effect of variation in the ICC. If we identify both cluster-randomised trials and individually-randomised trials, we plan to synthesise the relevant information. We will consider it reasonable to combine the results from both if there is little heterogeneity between the study designs and the interaction between the effect of intervention and the choice of randomisation unit is considered to be unlikely.

We planned to acknowledge heterogeneity in the randomisation unit and perform a sensitivity or subgroup analysis to investigate the effects of the randomisation unit.

Dealing with missing data

For included studies, we noted levels of attrition. We did not include studies for analysis if more than 20% of participants were excluded, or if more than 20% of participants analysed were not in their original randomisation group and it was not possible to restore participants to the correct group.

For all outcomes, we carried out analyses on an intention-to-treat basis, i.e. we included all participants randomised to each group in the analyses, and all participants analysed in the group to which they were allocated, regardless of whether or not they received the allocated intervention. The denominator for each outcome in each trial was the number randomised minus any participants whose outcomes were known to be missing.

Assessment of heterogeneity

We assessed statistical heterogeneity in each meta-analysis using the T2, I² and Chi² statistics. We regarded heterogeneity as substantial if I2 is greater than 30% and either T2 is greater than zero, or there is a low P-value (< 0.10) in the Chi² test for heterogeneity. 

Assessment of reporting biases

In future updates of this review, if there are 10 or more studies in the meta-analysis we will investigate reporting biases (such as publication bias) using funnel plots. We will assess funnel plot asymmetry visually, and use formal tests for funnel plot asymmetry. For continuous outcomes we will use the test proposed by Egger 1997, and for dichotomous outcomes we will use the test proposed by Harbord 2006. If asymmetry is detected in any of these tests or is suggested by a visual assessment, we will perform exploratory analyses to investigate it.

Data synthesis

We carried out statistical analysis using the Review Manager software (RevMan 2008). We used fixed-effect meta-analysis for combining data where it was reasonable to assume that studies were estimating the same underlying treatment effect: i.e. where trials were examining the same intervention, and the trials’ populations and methods were judged sufficiently similar. In future updates of this review, if there is clinical heterogeneity sufficient to expect that the underlying treatment effects differ between trials, or if substantial statistical heterogeneity is detected, we will use random-effects meta-analysis to produce an overall summary if an average treatment effect across trials is considered clinically meaningful. We will treat the random-effects summary as the average range of possible treatment effects and we will discuss the clinical implications of treatment effects differing between trials. If the average treatment effect is not clinically meaningful, we will not combine trials.

If we use random-effects analyses, we will present the results as the average treatment effect with its 95% confidence interval, and the estimates of  T² and I².

Subgroup analysis and investigation of heterogeneity

In future updates of this review, if we identify substantial heterogeneity, we will investigate it using subgroup analyses and sensitivity analyses. We will consider whether an overall summary is meaningful, and if it is, use random-effects analysis to produce it.

If there were sufficient studies, we intended to carry out the following subgroup analyses: by the infant age at introduction of the pacifier (0 to eight weeks, eight to 16 weeks, after 16 weeks), and by the duration of breastfeeding measured by the following:

  1. mean duration of exclusive breastfeeding (months);
  2. mean duration of any breastfeeding (months);
  3. proportion of infants exclusively or partially breastfed at four and six months of age.

Sensitivity analysis

In future updates of this review, as more data become available, we will carry out sensitivity analysis to explore the effect of trial quality. This will involve analysis based on our rating of selection bias and attrition bias. We will exclude studies of poor quality (those rated as 'unclear' or 'no') from the analysis in order to assess for any substantive difference to the overall result.

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Main results

Description of studies

Results of the search

The search identified nine reports of five randomised controlled trials (RCTs). We have included three studies and excluded two.

Included studies

See Characteristics of included studies. We included three studies involving 1915 babies (Jenik 2009; Kramer 2001; Schubiger 1997). However, only two of these studies (involving 1302 babies: Jenik 2009; Kramer 2001) contribute data to the analyses.

Jenik 2009: a multicentre-trial evaluated pacifier use in breastfeeding infants once lactation was well established for whether it reduced the prevalence or duration of breastfeeding. A total of 1021 mothers highly motivated to breastfeed were recruited and randomly assigned to whether pacifier was offered (n = 528) or not offered (n = 493). The study was designed as a non-inferiority trial and only mothers who were already successfully breastfeeding at two weeks and who indicated their intention to continue to do so for at least three months were enrolled. Mothers with breast problems that could interfere with breastfeeding (sore nipples, mastitis, inverted nipples, breast surgery) were not included. Participating mothers were interviewed at one, two, three, four, five, six, eight, 10 and 12 months after births or until breastfeeding ended. Interviews were conducted by a research assistant using a structured questionnaire designed to assess exclusive or any breastfeeding prevalence, duration of breastfeeding and whether the baby had used a pacifier. The primary outcome was prevalence of exclusive breastfeeding at three months. The main secondary outcomes were the prevalence of exclusive and any breastfeeding and duration of any breastfeeding. Primary analysis was by intention to treat. Comparison between the two groups in the study did not show any difference in the baseline characteristics namely the infant birthweight, mode of delivery, maternal age and education, and onset of breastfeeding.

Kramer 2001: a double-blind RCT, examined whether or not regular pacifier use is related to weaning by three months of age. A total of 281 healthy breastfeeding women who intended to breastfeed their infant longer and their healthy term singleton infants were randomised to one of two counselling interventions provided by a trained research nurse. In the experimental group (n = 140) the mother was asked to avoid pacifier use when the infant cried or fussed and to first offer the breast and, failing that, to try carrying or rocking the infant. In the control group (n = 141) all options were discussed for calming the infant, including breastfeeding, carrying, rocking and pacifier use. To ascertain the outcome mothers were asked to complete a validated behaviour diary on three consecutive days, when their infants were four, six and nine weeks of age. Study mothers were interviewed at three months by a research assistant who was blinded to the intervention status of the mother. A total of 258 (91.8%) mother-infant pairs completed three months follow-up.

Schubiger 1997: a multicentre prospective randomised trial evaluated whether avoidance of bottles and pacifiers in the first five days of life affected long-term breastfeeding performance. However, as a result of high attrition bias (more than 20% loss of participants), we have not included data from this study in the analysis. This is in accordance with our prespecified inclusion criteria for analysis.

Excluded studies

We have excluded two studies from the review (Collins 2004; Howard 2003). One study (Collins 2004) compared use of bottles and pacifiers versus cup feeding in preterm breastfeeding infants who wanted to breastfeed their infant. The other excluded study (Howard 2003) compared the effect of early versus late pacifier use in term infants on duration of breastfeeding. For further information, see Characteristics of excluded studies.

Risk of bias in included studies

All three included studies employed computerised central randomisation. The method of allocation concealment was 'adequate' in two studies (Jenik 2009; Kramer 2001). These two studies used consecutively numbered, opaque sealed envelopes but in one of the trials (Schubiger 1997) the method of concealment was 'unclear', as it reported use of sealed envelopes but did not state whether these were sequentially numbered. Two studies reported blinding of research nurse and outcome assessors (Jenik 2009; Kramer 2001). In both studies blinding of the care-giver was not mentioned. It would not be feasible to blind participants to the intervention. One study did not mention whether there was any blinding. Overall, the dropout rate was less than 10% from both arms, i.e. 4.9% versus 4.5% in Jenik 2009, 9.3% versus 7.1% in Kramer 2001 respectively. However, in Schubiger 1997, the total dropout rate was 45% versus 10.5% which did not satisfy our prespecified inclusion criteria for analysis. We detected no selective reporting or other potential source of bias in any of the included studies.

Effects of interventions

Primary outcomes

We included two out of three RCTs enrolling 1302 healthy full-term breastfeeding infants for analysis (Jenik 2009; Kramer 2001). Both of the trials contributed to at least one of the primary outcomes, i.e. proportion of infants partially or exclusively breastfed at three and four months of age. Comparison between pacifier use (intervention) and restricted pacifier use (control) revealed that there was no significant difference in the proportion of infants exclusively breastfed at three months (risk ratio (RR) 0.99; 95% confidence interval (CI) 0.93 to 1.05, two studies, 1228 babies (Analysis 1.1)) and at four months of age (RR 0.99; 95% CI 0.92 to 1.06, one study, 970 babies (Analysis 1.2)). There was also no significant difference in the proportion of infants partially breastfed at three months (RR 1.00; 95%; CI 0.98 to 1.13, two studies, 1228 babies (Analysis 1.3)), or at four months (RR 1.01; 95% CI 0.98 to 1.03, one study, 970 babies (Analysis 1.4)). Thus, pacifier use in full-term breastfeeding infants after birth or after the establishment of lactation did not significantly affect the prevalence or duration of exclusive or partial breastfeeding up to the age of four months.

None of the included studies reported data on the other primary outcomes, i.e. mean duration of partial or exclusive breastfeeding.

Secondary outcomes

None of the included studies reported data on any of our prespecified secondary outcomes: rate of breastfeeding difficulties (mastitis, cracked nipples, breast engorgement); infant's health (dental malocclusion, otitis media, oral candidiasis; sudden infant death syndrome); maternal satisfaction and level of confidence in parenting; or mean episode/frequency of infant crying and fussing per day.

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Discussion

Our review suggests that, in highly motivated mothers, pacifier use was not associated with a reduction in the rate or duration of exclusive or partial breastfeeding, regardless of whether the pacifier was introduced before or after lactation has established.

The WHO 'Ten Steps To Successful Breastfeeding' are valuable guidelines for hospitals. Some recommendations however, are based on observational studies. The use of pacifier is a common practice in many populations and thus, without having a solid scientific evidence of its impact on breastfeeding duration, this recommendation should be reviewed. The proposed mechanism for the relationship between reduced breastfeeding and pacifier use is that when infants use pacifiers they tend to suck on the breast less, and as a result the milk supply is reduced, and subsequently fails. Our review contradicts the finding of a meta-analysis of 31 cross-sectional and cohort studies (Karabulut 2009) enrolling several thousand infants that reported the use of pacifiers was associated with shortened duration of exclusive and of any breastfeeding before six months of age (RR 2.02; 95% CI 1.62 to 2.51 and RR 2.76; 95% CI 2.08 to 3.7 respectively).

Our review consists of two multicentre RCTs involving six tertiary hospitals from two different countries, enrolling 1302 participants in total. The risk of bias of the included studies were generally low. Nevertheless, there was no significant heterogeneity found among the studies. Both trials showed consistently that pacifier use did not significantly affect duration of breastfeeding. The summary effects obtained in our results were all consistently between 0.99 and 1.01 and 95% CIs were narrow. The rate of pacifier use in the restricted pacifier use was about 40% in both studies hence this could have a diluting effect the summary estimate. However, in view of the consistent proximity to 1.0 with extremely tight 95% CIs, if there is any effect it must be extremely small.

Several factors might affect breastfeeding duration such as maternal age, education, social status, and unrestricted mother-infant contact, as well as psychosocial factors like maternal intention to breastfeed, self-efficacy, breastfeeding confidence and earlier experience of breastfeeding (Kronborg 2004; Righard 1998). Comparison of baseline characteristics of the participants in both included trials showed no significant difference in the maternal age, education, and social and parity status. Mothers enrolled into these trials were highly motivated to continue breastfeeding. Jenik 2009 included only mothers who had successfully established breastfeeding after two weeks, while Kramer 2001 enrolled mothers after childbirth before lactation was established. In spite of the high motivation level of women in both of the included trials the breastfeeding rates at three months was very different, 34% in Kramer compared with more that 85% in Jenik, suggesting that the effect of the intervention would be similar across a range of breastfeeding rates. Thus, our review concludes that pacifier use before or after breastfeeding is established does not affect duration of breastfeeding when mothers are motivated to breastfeed their infants. The finding of this review, however, may not apply to mothers who are less motivated or who have no desire to breastfeed their infants longer.

Both studies in the review also reported that a proportion of mother-infant pairs in the trial did not comply with the recommendation to which they were randomised. This rate of non-compliance is not surprising in a population of diverse cultural background. Real-life situations such as intense infant crying, and infant preferences, may have influenced the use of pacifiers. This result is consistent with the intention-to-treat analysis, suggesting that recommending the use of a pacifier in a similar population does not influence breastfeeding success or duration. Kramer 2001 reported no significant difference in the mean frequency of cry and fuss behaviour per day between the pacifier users and non-users at six weeks and nine weeks of age. However, the study did not contribute sufficient data to allow this outcome to be analysed.

This review was unable to evaluate any of the secondary outcomes (the effect of pacifier use on breastfeeding difficulties faced by the mothers, and the effect of pacifier on long-term infant health, e.g. dental malocclusion, otitis media, dental caries and sudden infant death syndrome). Thus, to answer these questions, we recommend a RCT to evaluate these effects.

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Authors' conclusions

Implications for practice

In motivated mothers, there is moderate evidence that pacifier use in healthy term breastfeeding infants before and after lactation is established does not reduce the duration of breastfeeding up to four months of age. However, there is insufficient information on the potential harms of pacifiers on infants and mothers. In the light of the current review we recommend that until further information becomes available on the effects of pacifiers on the infant, mothers who are well motivated to breastfeed be enabled to make a decision on the use of a pacifier based on personal preference.

Implications for research

Further research is recommended to address the effect of pacifier use on duration of breastfeeding that include less motivated women. We also recommend well-designed RCTs to assess the rate breastfeeding difficulties faced by mothers associated with pacifier use and the long-term effect of pacifier use on mother and infant health.

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Acknowledgements

We would like to acknowledge the contributions of the SEA-ORCHID External Web Site Policy group and members of the Cochrane Australasian Centre.

As part of the pre-publication editorial process, this review has been commented on by two peers (an editor and referee who is external to the editorial team), a member of the Pregnancy and Childbirth Group's international panel of consumers and the Group's Statistical Adviser.

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Contributions of authors

Sharifah Halimah is the main author and guarantor for the review. She wrote the first draft of the protocol; provided a clinical and policy perspective as well as providing general advice on the development of the protocol. For the review she assessed studies for inclusion, assessed trial quality and extracted and analysed the data and wrote the review.

Shayesteh Jahanfar provided a input into the protocol development as well as the review. She independently assessed the quality of the trials, extracted and analysed the data. She also wrote the plain language summary of the review.

Mubashir Angolkar provided general comment, proof read the draft of the protocol as well as the review.

Jacqueline Ho provided general comments and advice from the protocol development to the completion of the review. She assessed trial quality where disagreement arose in the decision to include or exclude trials.

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Declarations of interest

None known.

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Differences between protocol and review

The methods have been updated to reflect the latest Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2009) and the Cochrane Pregnancy and Childbirth Group's methodological guidelines.

The title has been changed from "Pacifier use versus no pacifier use in breastfeeding term infants for increasing duration of breastfeeding" to "Effect of restricted pacifier use on breastfeeding duration", as detailed in the authors' response to feedback - see Feedback 1.

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Published notes

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Characteristics of studies

Characteristics of included studies

Jenik 2009

Methods

A multicentre, non-inferiority, RCT. The randomisation was carried out centrally with consecutively numbered, sealed, opaque envelopes containing random generated numbers constructed by an independent statistician.

Participants

1021 mothers highly motivated to breastfeed their term newborns of birthweight 2500g or more and who regained weight by 15 days postpartum, were assigned to offer or not to offer pacifiers as part of the advice given on how to comfort crying infants. Mothers with breast problems that could interfere with breastfeeding were not included in the study.

Interventions

The group offered pacifiers (n = 528) received a package containing 6 silicone pacifiers and a written guide for parents. They were also informed that other pacifiers could be use according to their preference.

The group that were not offered pacifier use (n = 493) received a guide with other alternatives for comforting a crying baby.

At the 3-month assessment, complete data for 499 mother-infants pairs in the group offered pacifiers and 471 in the group not offered pacifiers were available for the main outcome analysis.

Outcomes

Primary outcomes: the prevalence of exclusive breastfeeding at 3 months.

Secondary outcomes: prevalence of exclusive and any breastfeeding at specified ages and duration of any breastfeeding.

Notes

The study was carried out at 5 tertiary centres in Argentina. The author stated that the sponsor (International Children Medical Research Association, Switzerland) had no role in any part of the study. However, they acknowledge helpful advice from Peter Weiss, a consultant from a pacifier manufacturer who may be the same Peter Weiss who is the vice president of the funding body.

Risk of bias table
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk

It is reported that the randomisation was carried out centrally with random generation conducted by an independent statistician.

Allocation concealment (selection bias) Low risk

Consecutively numbered, sealed opaque envelopes were used to conceal a randomly generated assignment. A series of 500 envelopes was given to research assistants at each participating hospital with instructions to open the envelopes in numerical sequence and to assign the dyads to the corresponding group.

Blinding (performance bias and detection bias) Low risk

The outcome assessors were 'blinded to the group assignment' but there was no mention of whether the researchers were blinded to the group assignment. Participant blinding was not feasible.

Incomplete outcome data (attrition bias) Low risk

4.9% (26/528) participants in offer pacifier group and 4.5% (22/493) in the non-offer pacifier group were lost to follow-up due to various reasons.

Selective reporting (reporting bias) Low risk

None detected.

Other bias Unclear risk

Unsure of conflict of interest between the funding body and the researcher.

Kramer 2001

Methods

Double-blinded RCT.

Participants

A total of 281 healthy breastfeeding women and their healthy term singleton infants.

Interventions

Participants were randomly allocated to 1 of 2 counselling interventions provided by a research nurse trained in lactation counselling. A basic breastfeeding promotion package was included in both the intervention and control groups.

The intervention group (n = 140) were 'asked to avoid pacifiers when the infant cried or fussed' and suggested alternative ways to provide comfort.

The control group (n = 141) 'all options were discussed for calming an infant' including pacifier use .

Outcomes

Mothers was asked to complete a validated behaviour diary on 3 consecutive days, at 4, 6 and 9 weeks of age. Study mothers were interviewed at 3 months.

Primary outcome measures: rate of early weaning at 3 months, 72 hour infant behaviour logs detailing frequency and duration of crying and fussing and pacifier use at 4, 6, 9 weeks.

Notes

The trial was carried out from January 1998 to August 1999 on women giving birth at the Royal Victoria Hospital, a McGill University-affiliatted maternity hospital in Montreal, Quebec.

Risk of bias table
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk

'Randomization within each stratum was accomplished using computer-generated random numbers in blocks of 4'. 'Women were stratified by parity and if multiparous according to whether they had breastfed previously.'

Allocation concealment (selection bias) Low risk

'The assigned allocation was contained in an opaque envelope opened by a research nurse after the consent was obtained'.

Blinding (performance bias and detection bias) Low risk

'Study mothers were interviewed at 3 months by a research assistant who was blinded to the intervention status of the mother.'

Incomplete outcome data (attrition bias) Low risk

8.2% (23/281) participants, i.e. 13/140 from pacifier avoidance group, 10/141 from pacifier advised group lost to follow-up and did not complete the trial.

Selective reporting (reporting bias) Low risk

None detected.

Other bias Low risk

None detected.

Schubiger 1997

Methods

Multicentre prospective randomised trial (from 10 centres).

Participants

A total of 602 healthy full-term infants (> 37 weeks of gestation, birthweight 2750 g to 4200 g) of mothers who intended to stay in the hospital for 5 days postpartum and planned to breastfeed for more than 3 months.

Interventions

UNICEF group (n = 294): 'bottles, teats and pacifiers were strictly forbidden'; 'supplements if medically indicated were administered by cup or spoon'.

Standard group (n = 308): 'pacifiers were offered to all infants without restriction. Supplements were conventionally offered by bottle after breastfeeding'.

In both groups, the fluid supplements during the first few days consisted of a 10% dextrin-maltose solution. Fluid supplements were considered to be medically indicated in the following situations: babies agitated or screaming after breastfeeding; signs of dehydration (no urine output over 4 hours after day 1); symptoms of hypoglycaemia with blood glucose < 2 mmol/l. In the standard group fluids were more liberally offered.

About 180 participants in the UNICEF group and 291 participants in the standard group completed the protocol. Almost 40% of the participants in the UNICEF group violated protocol during the first 5 days in the hospital.

Upon discharge from the hospital, it was left to the mothers of both groups to decide whether to use a pacifier and/or bottle.

Outcomes

Incidence of breastfeeding at day 5, and at 2, 4, 6 months, proportion of fully or partially breastfeeding on day 5, sucking behaviour (good, mediocre, insufficient), incidence of fever, incidence of phototherapy. Questionaires administered to mothers at 2, 4, and 6 months were used to collect breastfeeding outcomes after hospital discharge.

Notes

Study conducted in Switzerland. Results were reported in 2 separate publications with slight differences in the presentation of results. This study however was not included for analysis due to high attrition bias (almost 40% loss of participants in the intervention group) due to protocol violation in the first weeks of the study.

Risk of bias table
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk

Centrally randomised, method of sequence generation not reported.

Allocation concealment (selection bias) Unclear risk

Sealed protocol forms distributed to each centre but it is not reported whether they were consecutively numbered or whether opaque envelopes were used.

Blinding (performance bias and detection bias) Unclear risk

There is no mention of blinding of researchers or outcomes assessors. Blinding of participants would not be feasible.

Incomplete outcome data (attrition bias) High risk

About 38% (114/294) of the participants in the UNICEF group were excluded due to protocol violation in the first week, i.e. mother requested a bottle (19), mother requested a pacifier (70), failed to spoon/cup feed (9), early discharge (6) and other reasons (10); leaving 180 participants in the UNICEF group. Similarly, in the control group 5.5% (n = 17) participants were excluded due to early discharge and other reasons. Subsequently there was a 6% (36/602) loss to follow-up (UNICEF 23, Standard 13).

Selective reporting (reporting bias) Low risk

None detected.

Other bias Low risk

None detected.

Footnotes

RCT: randomised controlled trial

Characteristics of excluded studies

Collins 2004

Reason for exclusion

This RCT aimed to determine the effect of artificial teats and cup on breastfeeding in preterm infants and not term infants, our prespecified inclusion criteria.

Howard 2003

Reason for exclusion

This RCT evaluated the effect of bottle feeding and pacifier use versus cup feeding and pacifier use in breastfeeding infants. Infants in both the intervention and the control group used pacifiers and hence there is no comparison between pacifier use and non pacifier use in breastfeeding infants.The study is excluded because the study population do not meet our inclusion criteria, as it included women who did not intend to breastfeed. Furthermore, the results for breastfeeding duration are presented as adjusted odds ratios and the primary data are not reported. Additionally, our review did not have an outcome 'breastfeeding at 5 weeks', as this is too short a duration to be clinically meaningful.

Footnotes

RCT: randomised controlled trial

Characteristics of studies awaiting classification

None noted.

Characteristics of ongoing studies

None noted.

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References to studies

Included studies

Jenik 2009

Jenik A, Vain N, Gorenstein A, Jacobi N, the Pacifier & Breastfeeding Study Group. Does the recommendation to use a pacifier influence the prevalence of breastfeeding? Results of a multicenter randomized clinical trial. Breastfeeding Medicine 2008;3(3):200.

Jenik A. Influence of pacifiers on breastfeeding duration. ClinicalTrials.gov (http://clinicaltrials.gov/) (accessed 20 February 2008).

* Jenik AG, Vain NE, Gorestein AN, Jacobi NE; for the Pacifier and Breastfeeding Trial Group. Does the recommendation to use a pacifier influence the prevalence of breastfeeding? Journal of Pediatrics 2009;155(3):350-4.

Kramer 2001

* Kramer MS, Barr RG, Dagenais S, Yang H, Jones P, Ciofani L, et al. Pacifier use, early weaning, and cry/fuss behavior: a randomized controlled trial. JAMA 2001;286(3):322-6.

Kramer MS, Barr RG, Jane R, Yang H, Dagenais S, Jones P, et al. Pacifier use, breastfeeding, and infant CRY/FUSS behavior: a randomized trial. Pediatric Research 2000;47(4):203A.

Schubiger 1997

Kind C, Schubiger G, Schwarz U, Tonz O. Provision of supplementary fluids to breast fed infants and later breast feeding success. Advances in Experimental Medicine & Biology 2000;478:347-54.

* Schubiger G, Schwarz U, Tonz O. UNICEF/WHO baby-friendly hospital initiative: Does the use of bottles and pacifiers in the neonatal nursery prevent successful breastfeeding? European Journal of Pediatrics 1997;156:874-7.

Excluded studies

Collins 2004

Collins CT, Ryan P, Crowther CA, McPhee AJ, Paterson S, Hiller JE. Effect of bottles, cups, and dummies on breast feeding in preterm infants: a randomised controlled trial. BMJ 2004;329(7459):193-8.

Howard 2003

Howard CR, Howard FM, Lanphear B, Eberly S, deBlieck EA, Oakes D, et al. Randomized clinical trial of pacifier use and bottle-feeding or cupfeeding and their effect on breastfeeding. Pediatrics 2003;111(3):511-8.

Studies awaiting classification

None noted.

Ongoing studies

None noted.

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Other references

Additional references

Aarts 1999

Aarts C, Hornell A, Kylberg E, Hofyander Y, Gebre-Medhin M. Breastfeeding patterns in relation to thumb sucking and pacifier use. Pediatrics 1999;104(4):e50.

Barros 1995

Barros FC, Victora CG, Semer TG, Tonioli Filho S, Tomasi E, Weiderpass E. Use of pacifiers is associated with decreased breastfeeding duration. Pediatrics 1995;95:497-9.

Caglar 2005

Caglar E, Larsson E, Andersson EM, Hauge MS, Ogaard B, Bishara S et al. Feeding, artificial sucking habits, and malocclusion in 3-year-old girls in different regions of the world. Journal of Dentition in Children 2005;72(1):25-30.

Chandra 1979

Chandra RK. Prospective studies on the effect of breastfeeding on the incidence of infection and allergy. Acta Pediatrica Scandanavia 1979;68(5):691-4.

Darwazeh 1995

Darwazeh AM, Al Bashir A. Oral candidal flora in healthy infants. Journal of Oral Pathological Medicine 1995;24:361-4.

Egger 1997

Egger M, Davey Smith G, Schneider M, Minder C. Bias in meta-analysis detected by a simple, graphical test. BMJ 1997;315(7109):629-34.

Gomes 2006

Gomes CF, Trezza EM, Murade EC, Padovani CR. Surface electromyography of facial muscles during natural and artificial feeding of infants. Journal of Pediatrics 2006;82(2):85-6.

Harbord 2006

Harbord RM, Egger M, Sterne JA. A modified test for small-study effects in meta-analyses of controlled trials with binary endpoints. Statistics in Medicine 2006;25(20):3443-57.

Higgins 2009

Higgins JPT, Green S, editors. Cochrane Handbook for Systematic Reviews of Interventions Version 5.0.2 [updated September 2009]. The Cochrane Collaboration, 2009. Available from www.cochrane-handbook.org.

Howard 1999

Howard CR, Howard FM, Lanphear B, DeBlieck EA, Eberly S, Lawrence RA. The effects of early pacifier use on breastfeeding duration. Pediatrics 1999;103(3):e133.

Jackson 1999

Jackson JM, Mourino AP. Pacifier use and otitis media in infants twelve months of age or younger. Pediatric Dentition 1999;21(4):255-60.

Karabulut 2009

Karabulut E, Songul Yalcin S, Ozdemir Geyik P, Karaagaolu E. Effect on pacifier use on exclusive and any breastfeeding: meta-analysis. Turkish Journal of Paediatrics 2009;51:35-43.

Kronborg 2004

Kronborg H, Vaeth M. The influence of psychosocial factors on the duration of breastfeeding. Scandinavian Journal of Public Health 2004;32(3):210-6.

Labbok 1990

Labbok M, Kosovec K. Towards consistency in breastfeeding definition. Studies in Family Planning 1990;21(4):226-30.

Mascarenhas 2006

Mascarenhas ML, Albernaz EP, Da Silva MB, Da Silviera RB. Prevalence of exclusive breastfeeding and its determiners in the first 3 months of life in South Brazil. Journal de Pediatria 2006;82(4):289-94.

Mitchell 2006

Mitchell EA, Blair PS, L'Hoir MP. Should pacifiers be recommended to prevent sudden infant death syndrome? Pediatrics 2006;117(5):1811-2.

Neifert 1995

Neifert M, Lawrence RA, Seacat J. Nipple confusion: toward a formal definition. Journal of Pediatrics 1995;126:S125-S129.

Neville 1988

Neville MC, Keller R, Seacat J, Lutes V, Neifert M, Casey C et al. Studies in human lactation: milk outputs in lactating women during the onset of lactation and full lactation. American Journal of Clinical Nutrition 1988;48(6):1375-86.

Oddy 2001

Oddy WH. Breastfeeding protects against illness and infection in infants and children: a review of evidence. Breastfeed Review 2001;9(2):11-8.

RevMan 2008

Review Manager (RevMan) [Computer program]. Version 5.0. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2008.

Righard 1992

Righard L, Alade MO. Sucking technique and its effect on success of breastfeeding. Birth 1992;19(4):185-9.

Righard 1998

Righard L. Are breastfeeding problems related to incorrect breastfeeding technique and the use of pacifiers and bottles? Birth 1998;25(1):40-4.

Saririan 2006

Saririan S, Hauck FR. New recommendations to reduce the risk of SIDS: what should we advise parents. American Family Physician 2006;74(11):1864-9.

Scott 2005

Scott JA, Binns CW, Oddy WH, Graham KI. Predictors of breastfeeding duration: evidence from a cohort study. Pediatrics 2005;117:e646-e655.

Ullah 2003

Ullah S, Griffiths P. Does the use of pacifiers shorten breastfeeding duration in infants. British Journal of Community Nursing 2003;8(10):458-63.

Victora 1997

Victora CG, Behague DP, Barros FC, Olinto MT, Weiderpass E. Pacifier use and short breastfeeding duration: cause, consequence, or coincidence? Pediatrics 1997;99(3):445-53.

Vogel 2001

Vogel AM, Hutchison BL, Mitchell EA. The impact of pacifier use on breastfeeding: a prospective cohort study. Journal of Paediatrics and Child Health 2001;37(1):58-3.

Other published versions of this review

Jaafar 2011

Jaafar SH, Jahanfar S, Angolkar M, Ho JJ. Pacifier use versus no pacifier use in breastfeeding term infants for increasing duration of breastfeeding. Cochrane Database of Systematic Reviews 2011, Issue 3. Art. No.: CD007202. DOI: 10.1002/14651858.CD007202.pub2.

Classification pending references

Collins 2004

Collins CT, Ryan P, Crowther CA, McPhee AJ, Paterson S, Hiller JE. Effect of bottles, cups, and dummies on breast feeding in preterm infants: a randomised controlled trial. BMJ 2004;329(7459):193-8.

Howard 2003

Howard CR, Howard FM, Lanphear B, Eberly S, deBlieck EA, Oakes D et al. Randomized clinical trial of pacifier use and bottle-feeding or cupfeeding and their effect on breastfeeding. Pediatrics 2003;111(3):511-8.

Jenik 2008

Jenik A. Influence of pacifiers on breastfeeding duration. ClinicalTrials.gov (www.clinicaltrials.gov) (accessed 20 February 2008).

Jenik 2008a

Jenik A, Vain N, Gorenstein A, Jacobi N, the Pacifier & Breastfeeding Study Group. Does the recommendation to use a pacifier influence the prevalence of breastfeeding? Results of a multicenter randomized clinical trial. Breastfeeding Medicine 2008;3(3):200.

Kind 2000

Kind C, Schubiger G, Schwarz U, Tonz O. Provision of supplementary fluids to breast fed infants and later breast feeding success. Advances in Experimental Medicine & Biology 2000;478:347-54.

Kramer 2001

Kramer MS, Barr RG, Dagenais S, Yang H, Jones P, Ciofani L et al. Pacifier use, early weaning, and cry/fuss behavior: a randomized controlled trial. JAMA 2001;286(3):322-6.

Schubiger 1997

Schubiger G, Schwarz U, Tonz O. UNICEF/WHO baby-friendly hospital initiative: Does the use of bottles and pacifiers in the neonatal nursery prevent successful breastfeeding? European Journal of Pediatrics 1997;156:874-7.

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Data and analyses

1 Pacifier use versus pacifier restriction

Outcome or Subgroup Studies Participants Statistical Method Effect Estimate
1.1 Proportion of infants exclusively breastfed at 3 months 2 1228 Risk Ratio (M-H, Fixed, 95% CI) 0.99 [0.93, 1.05]
1.2 Proportion of infants exclusively breastfed at 4 months 1 970 Risk Ratio (M-H, Fixed, 95% CI) 0.99 [0.92, 1.06]
1.3 Proportion of infants partially breastfed at 3 months 2 1228 Risk Ratio (M-H, Fixed, 95% CI) 1.00 [0.98, 1.02]
1.4 Proportion infants partially breastfed at 4 months 1 970 Risk Ratio (M-H, Fixed, 95% CI) 1.01 [0.98, 1.03]

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Sources of support

Internal sources

  • University Kuala Lumpur Royal College of Medicine Perak, Malaysia
  • Penang Medical College, Malaysia
  • Jawaharlal Nehru Medical College Campus, Belgaum, India
  • Ipoh Specialist Hospital, Perak, Malaysia

External sources

  • SEA ORCHID, Malaysia

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Feedback

1 Di Mario, 06 July 2011

Summary

Pacifier use and breastfeeding [1] is  an issue that is highly relevant to health professionals and families, for example this topic was the most accessed among Evidence Updates registrants (http://plus.mcmaster.ca/EvidenceUpdates External Web Site Policy) and it is relevant to one of the ten steps to successful breastfeeding of the WHO-UNICEF Baby Friendly Hospital Initiative [2]. 

We believe that this Cochrane review, stating that pacifier does not reduce breastfeeding rates, is severely flawed and biased and therefore should be promptly revised. Here below is our criticism in detail. 

The analysis is based only on two randomized controlled trials (RCTs) [3,4]. Validity of the review authors conclusions is limited as they have excluded from the review a third RCT which shows an association  between pacifier use and breastfeeding discontinuation at four weeks [5]. The reason for this exclusion is reported as being that both groups were exposed to pacifier. Actually, the intervention group was exposed to pacifier soon after birth while the control group was advised to avoid pacifiers up to five weeks of life of the newborn. Therefore, data comparing breastfeeding practice before five weeks of life could have been appropriately included in the review, or at least commented on. 

In addition, the two studies included in the review were not designed to answer the clinical question about the effect of pacifier use for healthy full-term newborns whose mothers have initiated breastfeeding and intend to exclusively breastfeed, on the duration of breastfeeding. These two trials assessed the effects on breastfeeding of interventions aimed at reducing the use of pacifiers; they did not assess the effect of pacifiers on breastfeeding. Mothers in the pacifier group used it in 71% of cases, while mothers in not pacifier group used it in 44% of cases (overall rates). Contamination between two treatment arms points to no difference or inconclusive results. Your conclusions of a null effect of pacifier on breastfeeding success based only on two studies with high contamination rate are therefore falsely reassuring. 

Major problems of the studies included in the review are insufficiently discussed. The larger of the two included studies (1021 infants out of a total of 1302) [3], has exclusion and inclusion criteria so strict that the population observed is extremely selected, limiting the external validity of the conclusions, which is not even mentioned. For example, participating hospitals had established breastfeeding programs, with early initiation of breastfeeding, lactation consultants, and unrestricted rooming-in. Mothers were encouraged to avoid pacifier use until breastfeeding was well established. At term healthy infants, exclusively breastfeeding, whose mothers reported an intention to breastfeed for at least three months, not using pacifiers and with lactation well established at the age of 2 weeks were included. Exclusion criteria were breast problems that could interfere with breastfeeding (persistently sore nipples, mastitis, earlier breast surgery, and severely flat or inverted nipples). Mothers who communicated a preference in the introduction or not of a pacifier were also excluded. Further evidence that this study assessed an extremely selected population of women is the remarkably high rate of exclusive breastfeeding at three months for both groups (> 85%), much higher than the rate of exclusive breastfeeding at three months commonly seen in Europe (e.g. 47% in Italy in 2008, and in Sweden ranging between 68% at four months and 79% at two months in 2002) [6,7]. Finally the authors of the study powered the sample to perform an analysis based on intention to treat, but as the trial was non-inferiority, the ‘according to protocol’ analysis would have been more appropriate [8]. Unfortunately, as the authors admit, the study sample was not sufficiently large to adequately perform this analysis. 

The second RCT included in the review also suggests that the null effect of pacifier on breastfeeding could be a false conclusion [4]. As there was a high contamination rate, results are presented based on actual exposure (observational analysis) in addition to the analysis based on randomized groups. This observational analysis showed a significant difference between pacifier users and not users for weaning by 3 months (RR: 1.9; 95%CI: 1.1, 3.3). Although observational studies are not reliable for assessing the association between pacifier use and breastfeeding practice, due to residual confounding and reverse causality, we think that RCTs with low compliance and high contamination, as in this study, cannot provide a valuable answer, especially when no differences among groups are detected. None of these issues were adequately discussed in this Cochrane review. 

Finally, we believe that a potentially very relevant conflict of interest in one of the trials included [3] was not mentioned: the authors of the study report as a funding source an association (the International Children Medical Research Association) whose characteristics are unclear, since it is not possible to find any information on it in the web. The only other citation of this association we have traced is a letter by Dr Peter PW Weiss to Pediatrics [9] criticizing a paper that reported a relationship between reduced pacifier use and reduced acute otitis media incidence. Is he maybe the same Peter Weiss, consultant for a manufacturer of pacifiers, that appears in the acknowledgment section of the trial report [3]? A Dr Peter Weiss is also the vice-president (the president is unknown) of the International Children Medical Research Society, which is, maybe, another name of the International Children Medical Research Association, created in Switzerland by a company founded by the same manufacturers of pacifiers. Should this be made clear to the readers of the Cochrane review? 

Our view is that these issues raise questions about the validity of the conclusions of this Cochrane review.  Considering that Cochrane reviews represent a seal of quality among health professionals and the public, we think that it is responsibility of the Cochrane Collaboration to scrutinize the evidence selection, its critical appraisal and the validity of the conclusions, specially for a hot topic relevant for public health, as is the case for breastfeeding.

Simona Di Mario1, Adriano Cattaneo2, Vittorio Basevi1, Nicola Magrini1

1 NHS CeVEAS, NHS Centre for the Evaluation of the Effectiveness of Health Care, WHO Collaborating Centre for Evidence-based Research Synthesis and Guideline Development in Reproductive Health, Emilia-Romagna, V. le L. Muratori 201, Modena, Italy, 41100
2 Unit for Health Services Research and International Health, WHO Collaborating Centre for Mother and Child Health, Institute of Child Health, IRCCS Burlo Garofolo, Trieste, Italy

References

  1. Jaafar SH, et al. Pacifier use versus no pacifier use in breastfeeding term infants for increasing duration of breastfeeding. Cochrane Database Syst Rev. 2011 Mar 16;3:CD007202. 
  2. Kramer MS, et al; PROBIT Study Group (Promotion of Breastfeeding  Intervention Trial). Promotion of Breastfeeding Intervention Trial (PROBIT): a randomized trial in the Republic of Belarus. JAMA 2001;285:413-20. 
  3. Jenik AG, et al; Pacifier and Breastfeeding Trial Group. Does the recommendation to use a pacifier influence the prevalence of breastfeeding? J Pediatr 2009;155:350-4.e1.
  4. Kramer MS, et al. Pacifier use, early weaning, and cry/fuss behavior: a randomized controlled trial. JAMA 2001;286:322-6.
  5. Howard CR, et al. Randomized clinical trial of pacifier use and bottle-feeding or cupfeeding and their effect on breastfeeding. Pediatrics 2003;111:511-8.
  6. Cuoghi C, et al. Prevalence of breastfeeding in Emilia-Romagna Region in 2008. [Prevalenza dell'allattamento al seno in Emilia-Romagna. Ricerca anno 2008] Fifth Edition. Bologna: Regione Emilia-Romagna; 2010 [Italian].
  7. Statistics Health and Diseases. Breast-feeding, children born 2002. The National Board of Health and Welfare. Centre for epidemiology. Stockholm 2004 [Swedish, English summary].
  8. Gøtzsche PC. Lessons from and cautions about noninferiority and equivalence randomized trials. JAMA 2006;295:1172-4 9. Weiss PP, Nowak AJ. Pacifier as a risk factor for acute otitis media. Pediatrics 2002;109:351-2.

Reply

We thank De Mario et al for their comments, and have responded in the order they made their comments.

We disagree that our review is ‘severely flawed and biased’. The protocol and review have been prepared according to Cochrane methods.

The study by Howard et al is excluded because the study population do not meet our inclusion criteria, as it included women who did not intend to breastfeed. Also, the results for breastfeeding duration are presented as adjusted odds ratios and the primary data are not reported.  Finally, our review did not have an outcome ‘breastfeeding at five weeks, as this is too short a duration to be clinically meaningful. Whilst preparing this response we noticed that the text in ‘types of participants’ was not as explicit as the text in our objectives. We have therefore modified ‘types of participants’ so that it matches the objectives. 

We agree our review is about the effect of recommending restricted pacifier use. For clarification we have modified the title of the review, and the background text. This clarification also means that contamination between the two intervention groups is no longer an issue. In addition, we disagree that contamination could have been the reason for the null effect. If the high baseline rate of pacifier use had any diluting effect on the final pooled results it would be very small, as the relative risks were consistently close to 1.00 with extremely tight confidence intervals. This is now clarified in the discussion.

Di Mario, Cattaneo, Basevi and Magrini wrote: Major problems of the studies included in the review are insufficiently discussed. The larger of the two included studies (1021 infants out of a total of 1302) [3] has exclusion and inclusion criteria so strict that the population observed is extremely selected, limiting the external validity of the conclusions, which is not even mentioned. For example, participating hospitals had established breastfeeding programs, with early initiation of breastfeeding, lactation consultants, and unrestricted rooming-in. Mothers were encouraged to avoid pacifier use until breastfeeding was well established. At term healthy infants, exclusively breastfeeding, whose mothers reported an intention to breastfeed for at least three months, not using pacifiers and with lactation well established at the age of two weeks were included. Exclusion criteria were breast problems that could interfere with breastfeeding (persistently sore nipples, mastitis, earlier breast surgery, and severely flat or inverted nipples). Mothers who communicated a preference in the introduction or not of a pacifier were also excluded. Further evidence that this study assessed an extremely selected population of women is the remarkably high rate of exclusive breastfeeding at three months for both groups (> 85%), much higher than the rate of exclusive breastfeeding at three months commonly seen in Europe (e.g. 47% in Italy in 2008, and in Sweden ranging between 68% at four months and 79% at two months in 2002) [6,7]. Finally the authors of the study powered the sample to perform an analysis based on intention to treat, but as the trial was non-inferiority, the ‘according to protocol’ analysis would have been more appropriate [8]. Unfortunately, as the authors admit, the study sample was not sufficiently large to adequately perform this analysis.

The report of Jenik 2009 does not state this was a non-inferiority trial. Whilst an ‘according to protocol analysis’ might have been appropriate for this trial, that is not relevant for this review as we specified we would use intention-to-treat analysis, which complies with Cochrane methods. We have included a paragraph in the discussion about external validity of the included trials.

We agree that the high contamination between intervention groups in Kramer 2001 may have had a diluting effect, and have included this in the discussion.

Jenik 2009 states that the sponsors had no role in any part of the study. However, the report does acknowledge helpful advice from Peter Weiss. We agree this may be the same Peter Weiss who is the vice president of the funding body, as well as a consultant for a pacifier company.  We have now included this information in the Table of ‘Characteristics of Included Studies’.

Contributors

Jacqueline J Ho, Sharifah Halimah Jaafar, Shayesteh Jahanfar

2 Paulussen, 21 March 2012

Summary

There is a mistake in this review. In the table of characteristics of included studies, Kramer 2001 is stated to have 140 women in the intervention group (avoid pacifiers), and 141 women in the control group (use a pacifier). Under incomplete data it states data were available for 127 women in the intervention group (avoid pacifiers) and 131 in the control group (use a pacifier). In the data analysis, data for this study from the intervention and control group are switched. It should be 44/131 for the use pacifier group (not 46/127) and 46/127 for the avoid pacifier group (not 44/131). This means that the total and risk ratio are also incorrect.

[Feedback received from Valérie Paulussen, 7 February 2012] 

Reply

We thank Valérie Paulussen for pointing out this mistake, which we have now corrected in this update. The correction does not alter or change the finding and conclusion of the review.

Contributors

Sharifah Halimah Jaafar


This review is published as a Cochrane review in The Cochrane Library, Issue 7, 2012 (see http://www.thecochranelibrary.com External Web Site Policy for information). Cochrane reviews are regularly updated as new evidence emerges and in response to feedback. The Cochrane Library should be consulted for the most recent recent version of the review.