Research on Breastfeeding & Breast Milk at the NICHD

NICHD Research Helps Define Benefits of and Inform Practices for Breastfeeding

woman breastfeeding infant

The process of breastfeeding does more than provide important nutrition and other things to support infants' growth and development; it also benefits mothers' health and offers an important opportunity for the pair to bond.

World Breastfeeding Week External Web Site Policy, from August 1 to August 7, is jointly sponsored by the World Health Organization (WHO) and United Nations Children's Fund (UNICEF) and will be celebrated in hundreds of countries. Events during the week aim to encourage breastfeeding as a way to improve the health of mothers and babies around the globe.

In the United States, the American Academy of Pediatrics (AAP) External Web Site Policy currently recommends that infants be fed mother's breast milk exclusively, by breastfeeding or by bottle-feeding milk expressed from the mother's breast, until they are at least 6 months old. "Exclusive" breastfeeding means that the infant does not receive any additional foods or fluids. Beyond the period of 6 months of exclusive breastfeeding, the AAP also suggests feeding mother's breast milk for up to 1 year of age in combination with solid foods.

Although breastfeeding is the "gold standard," not all women breastfeed their infants. According to UNICEF's State of the World's Children Report 2011, of the 136.7 million babies born worldwide each year, only 32.6% are breastfed exclusively for the first 6 months. Some mothers make the choice not to breastfeed, but others might be unable to breastfeed because of medical conditions, such as HIV, or other reasons, such as problems producing milk.

The NICHD supports and conducts many studies related to infant feeding, including breastfeeding and breast milk. Such studies include (but not limited to) the health benefits of breastfeeding and breast milk, identification of components of human milk (nutrients and bioactive components), factors that influence the composition of human milk, factors that influence the development and health of the mammary gland, the social and cultural impacts of breastfeeding and infant feeding, and the mechanisms by which human milk confers protection against disease. The NICHD also supports several networks that conduct breastfeeding research and other activities related to breastfeeding.

During this year's World Breastfeeding Week, the NICHD provides some examples of its breastfeeding research activities. Select a link below to learn more.

Impact of Breastfeeding and Breast Milk on Infant and Child Health
Breastfeeding Methods and Practices
Breast Health and Mammary Gland Development and Function
Breastfeeding and HIV Transmission and Exposure
Other Research and Activities Related to Breastfeeding

Impact of Breastfeeding and Breast Milk on Infant and Child Health

The NICHD supports many studies on the impact of breastfeeding and breast milk on infant health. This research includes efforts to understand nutritional components of breast milk, as well as its bioactive components—those that have an effect on cells and tissues—and how these components contribute to development and protect against disease.

Among the bioactive components of breast milk is lactoferrin, which has been the focus of a number of clinical trials for its effectiveness in preventing diarrhea. Another very interesting group of compounds are the oligosaccharides, short chains of sugar molecules joined together by chemical bonds. These molecules are found in higher concentrations than most nutrients in human milk. Research has proven that these compounds play important roles in the natural defenses of breastfed infants by preventing disease-causing bacteria and viruses from infecting the intestines. Additional research has also shown that consuming oligosaccharides in breast milk reduces the risk of respiratory illness.

Ongoing work supported through the Institute's Endocrinology, Nutrition, and Growth (ENG) Branch aims to create versions of these components to protect against disease and prevent and treat infections, while not contributing to drug resistance. For more information on this research area, check out the ENG Branch Report to the NACHHD Council, sections on "Lactation and Milk Composition" and "Bioactive Components of Human Milk."

Findings from selected NICHD-supported studies include the following:

  • Clinical studies of lactoferrin in children.
    Ochoa TJ, Pezo A, Cruz K, Chea-Woo E, Cleary TG. (2012). Biochem Cell Biol, Jun;90(3), 457-467. Epub 2012 Mar 1. [PMID: 22380791]
  • Exclusive breast milk feeding lowers the risk of death and gastrointestinal disease in newborns. Meinzen-Derr J., Poindexter B., Wrage L., Morrow A.L., Stoll B., Donovan E.F. 2009. Role of human milk in extremely low birth weight infants' risk of necrotizing enterocolitis or death. Journal of Perinatology. 29(1), 57-62. [PubMed ID: 18716628]
  • Higher levels of adiponectin, a serum protein, in breast milk are associated with greater weight gain in breastfed infants. Woo, J. G., Guerrero, M. L., Guo, F., Martin, L. J., Davidson, B. S., Ortega, H. et al. (2012). Human milk adiponectin affects infant weight trajectory during the second year of life. Journal of Pediatric Gastroenterology and Nutrition, 54(4), 532-539. [PubMed ID: 22094897]
  • Exclusive breastfeeding reduces respiratory- and diarrhea-related deaths among infants born to HIV-infected women. Mwiru RS, Spiegelman D, Duggan C, Peterson K, Liu E, Msamanga G. et al. (2011). Relationship of exclusive breast-feeding to infections and growth of Tanzanian children born to HIV-infected women. Public Health Nutrition, 14(7), 1251-1258. [PubMed ID: 21324223]
  • Neonatal protection by an innate immune system of human milk consisting of oligosaccharides and glycans. Newburg DS. (2009). J Anim Sci, Apr;87(13 Suppl), 26-34. Epub 2008 Nov 21. [PMID: 19028867]

Promotion of Breastfeeding Intervention Trial (PROBIT)

The PROBIT study External Web Site Policy, which was partially funded by the NICHD, examined the influence of an intervention to promote breastfeeding. The PROBIT study consists of four individual studies: PROBIT I, II, and III are complete and PROBIT IV is in progress. The study is led by investigators from McGill University (Canada), the University of Bristol (United Kingdom), and Harvard University (United States). The PROBIT study is the largest cluster-randomized controlled trial ever conducted on breastfeeding. The study is based on the long-term follow-up of 17,046 healthy mothers and infants who were originally enrolled into the trial in the Republic of Belarus in Eastern Europe. The PROBIT continues to examine the effects of breastfeeding promotion on breastfeeding rates and the benefits of exclusive breastfeeding on infant health.

Some of the findings from the study included:

  • Breastfeeding promotion increases exclusive breastfeeding of infants and doubles the likelihood of a mother breastfeeding her next-born child.
    Kramer M.S., Fombonne E., Igumnov S., Vanilovich I., Matush L., Mironova E. et al. Promotion of Breastfeeding Intervention Trial (PROBIT) Study Group. 2008. Effects of prolonged and exclusive breastfeeding on child behavior and maternal adjustment: evidence from a large, randomized trial. Pediatrics, 121(3), e435-40. [PubMed ID: 18310164]
  • Prolonged and exclusive breastfeeding improves children's cognitive development. Kramer M.S., Aboud F., Mironova E., Vanilovich I., Platt R.W., Matush L. et al. Promotion of Breastfeeding Intervention Trial (PROBIT) Study Group. 2008. Breastfeeding and child cognitive development: new evidence from a large randomized trial. Archives of General Psychiatry, 65(5), 578-584. [PubMed ID: 18458209]
  • Prolonged or exclusive breastfeeding does not protect against asthma or allergy. Kramer M.S., Matush L., Vanilovich I., Platt R., Bogdanovich N., Sevkovskaya Z. et al. Promotion of Breastfeeding Intervention Trial (PROBIT) Study Group. 2007. Effect of prolonged and exclusive breast feeding on risk of allergy and asthma: cluster randomized trial. BMJ, 335(7624), 815. [PubMed ID: 17855282]

Study in Progress – Infant Feeding and Diabetes Risk

In type 1 diabetes mellitus (T1DM), the body's own immune system destroys the insulin-producing cells of the pancreas. Research shows that traditional baby formulas, often produced from cow's milk, contain complex milk proteins that are typically the initial targets of the immune response that later destroys the insulin-producing cells, which then leads to T1DM. Breast milk does not elicit the same immune system response, nor does hydrolyzed formula—milk formula that is treated to simplify the complex milk proteins so they better mimic the proteins found in breast milk, while still providing complete nutrition.

In the Trial to Reduce the Incidence of Type 1 Diabetes for those Genetically at Risk (TRIGR), a study supported through the NICHD ENG Branch and several other organizations, researchers are examining whether weaning infants from breast milk to a hydrolyzed formula, instead of a traditional non-hydrolyzed formula, reduces the risk of developing T1DM. For more information on this study, visit PubMed ID: 21653795.

Breastfeeding Methods and Practices

NICHD research on infant feeding isn't limited to the mechanics and biology of breastfeeding, but also includes studies of factors that affect breastfeeding methods, practices, and duration. Some of these factors include a woman's body image and the availability of space and/or time that she has to breastfeed or express milk at work. Breastfeeding duration may also be affected by how well an infant is suckling. The effects of breastfeeding duration and early weaning on infant health are important areas of supported NICHD research.

Some of the findings from recent studies supported by the NICHD on breastfeeding duration and infant health include: 

  • High BMI before pregnancy and poor body image reduce breastfeeding duration.
    Hauff L.E., Demerath E.W. (2012). Body image concerns and reduced breastfeeding duration in primiparous overweight and obese women. American Journal of Human Biology, 24(3), 339-349. [PubMed ID: 22308116]
  • Manual (or hand) expression of breast milk improves breastfeeding rates of poorly feeding infants compared to pump expression.
    Flaherman V.J., Gay B., Scott C., Avins A., Lee K.A., Newman T.B. (2012). Randomized trial comparing hand expression with breast pumping for mothers of term newborns feeding poorly. Archives of Disease in Childhood: Fetal and Neonatal Edition. 97(1), F18-23. [PubMed ID: 21747129]
  • State breastfeeding laws requiring employers to provide lactation rooms or leave time for breastfeeding do not alone increase breastfeeding duration.
    Dozier A.M., McKee K.S. (2011). State breastfeeding worksite statutes.…breastfeeding rates…and.….Breastfeeding Medicine, 6, 319-324. [PubMed ID: 22007820]
  • Perceptions of Primary Care-Based Breastfeeding Promotion Interventions: Qualitative Analysis of Randomized Controlled Trial Participant Interviews.
    Andaya E, Bonuck K, Barnett J, & Lischewski-Goel J. (2012). Breastfeed Med, May 23. Epub ahead of print. [PubMed PMID: 22621223]
  • What predicts intent to breastfeed exclusively? Breastfeeding knowledge, attitudes, and beliefs in a diverse urban population.
    Stuebe AM & Bonuck K. (2011). Breastfeed Med, Dec;6(6), 413-420. Epub 2011 Feb 22. [PubMed ID: 21342016]
  • Bottle-Weaning Intervention Tools: The "How" and "Why" of a WIC-Based Educational Flipchart, Parent Brochure, and Website.
    Hyden C, Kahn R, Bonuck K. (2012). Health Promot Pract, Apr 5. Epub ahead of print. [PubMed ID: 22491388]
  • Inappropriate bottle use: an early risk for overweight? Literature review and pilot data for a bottle-weaning trial.
    Bonuck KA, Huang V, & Fletcher J. (2010). Matern Child Nutr, Jan;6(1), 38-52. [PubMed ID: 20055929]
  • WIC participation, breastfeeding practices, and well-child care among unmarried, low-income mothers.
    Chatterji P, & Brooks-Gunn J. (2004). Am J Public Health, Aug;94(8), 1324-1327. [PubMed ID: 15284035]

Infant Feeding Practices Study II (IFPSII)

The NICHD co-funded IFPSII, a large longitudinal survey of 4,900 women enrolled before their babies were born, with the Centers for Disease Control and Prevention (CDC). The survey followed more than 2,000 women through to their infant's first birthday. Mothers received one questionnaire before their babies were born and then 10 questionnaires almost monthly after the baby's birth. Questions about breastfeeding were included in each post-birth questionnaire. 

Study researchers published 13 papers in a special supplement to the journal Pediatrics in 2008. To date, 24 papers have been published on various aspects of infant feeding, breastfeeding, and other aspects of maternal reproductive health and infant health from IFPSII data. The IFPSII dataset is now archived, but is available through the CDC website for scientists to use for additional analyses. Visit for a complete listing of publications from the IFPSII.

Breast Health and Mammary Gland Development and Function

Women's breast health is an important area of study for the NICHD and for other NIH Institutes, such as the National Cancer Institute. Good breast health, breast development, and mammary gland development and function are necessary to ensure optimal milk production and comfort during breastfeeding. These factors often affect how long a woman chooses to breastfeed and the quality of breast milk that she produces, which has a direct impact on infant health.

Some selected studies and research findings on breast health and mammary gland development include the following:

  • Symptoms of psychological depression during pregnancy alter the breast milk content, including fatty acids, which are crucial for infant health and development.
    Keim S.A., Daniels J.L., Siega-Riz A.M., Dole N., Herring A.H., Scheidt P.C. (2012). Depressive symptoms during pregnancy and the concentration of fatty acids in breast milk. Journal of Human Lactation, 28(2), 189-195. [PubMed ID: 22223516]
  • Repressor of estrogen receptor activity (or REA) is a protein essential for mammary gland development during puberty, maturation during pregnancy, and function during lactation.
    Park S., Zhao Y., Yoon S., Xu J., Liao L., Lydon J. et al. (2011). Repressor of estrogen receptor activity (REA) is essential for mammary gland morphogenesis and functional activities: studies in conditional knockout mice. Endocrinology, 152(11), 4336-4349. [PubMed ID: 21862609]
  • The protein adipophilin regulates mammary gland maturation into a functional milk-secreting organ during pregnancy.
    Russell T.D., Schaack J., Orlicky D.J., Palmer C., Chang B.H., Chan L. et al. (2011).Adipophilin regulates maturation of cytoplasmic lipid droplets and alveolae in differentiating mammary glands. Journal of Cell Science, 124(Pt 19), 3247-3253. [PubMed ID: 21878492]
  • ZnT4 protein transports zinc, a mineral that is secreted into breast milk and critical for infant health, in mammary epithelial cells.
    McCormick N.H., Kelleher S.L. (2012).ZnT4 provides zinc to zinc-dependent proteins in the trans-Golgi network critical for cell function and Zn export in mammary epithelial cells. AJP Cell Physiology, May 23. [Epub ahead of print] [PubMed ID: 22621784]

Breastfeeding and HIV Transmission and Exposure

Although breastfeeding is a cornerstone of infant survival in developing countries, it can also transmit HIV from mother to infant. The most effective way to eliminate this type of transmission is to use formula instead of breastfeeding, but this approach is neither safe nor feasible for most HIV-infected women in resource-limited settings because of cost, unsafe water supply, and low cultural acceptance of formula feeding. Infants who are not breastfed also miss out on the essential nutrition and immunologic defenses in breast milk that can be crucial for infant survival.

Clinical trials, such as the Post-Exposure Prophylaxis of the Infant (PEPI)-Malawi Study, which was jointly funded by the NICHD Pediatric, Adolescent, and Maternal AIDS (PAMA) Branch and the Centers for Disease Control and Prevention (CDC), have found that giving an antiretroviral drug called nevirapine to the breastfeeding infant reduces HIV transmission through breast milk. This study was featured in the NICHD Spotlight Research Advances in Pediatric, Adolescent, and Maternal HIV/AIDS.

In another analysis from the same study, the researchers also compared health outcomes of breastfed and non-breastfed uninfected HIV-exposed infants at 6 to 9 months of age, 9 to 12 months of age, and 12 to 15 months of age, showing the important benefits of breastfeeding for infants in resource-limited countries. They found that:

  • Non-breastfed Malawian infants were nearly twice as likely to develop illness or require hospitalization as were infants who continued breastfeeding during these time periods.
  • Rates of illness, malnutrition, and hospital admission were higher among infants who were not breastfed compared to those who were breastfed.
  • At 15 months of age, the risk of death was almost twice as high among infants who stopped breastfeeding compared to those who continued breastfeeding. For more information on this study, visit PubMed ID: 21810754.

Other clinical trials, such as the Kesho Bora study, also jointly funded by the NICHD PAMA Branch and CDC, have shown that combination antiretroviral drugs given to the woman during breastfeeding also reduces HIV transmission to breastfed infants.

  • Triple antiretroviral compared with zidovudine and single-dose nevirapine prophylaxis during pregnancy and breastfeeding for prevention of mother-to-child transmission of HIV-1 (Kesho Bora study): A randomized controlled trial.
    Kesho Bora Study Group, de Vincenzi I. (2011). Lancet Infect Dis., Mar;11(3), 171-180. [Pub Med ID:  21237718]

Thus far, NICHD-funded research has identified two effective interventions—giving an antiretroviral drug to the breastfed infant or giving antiretroviral drugs to the breastfeeding mother—that can allow for safer breastfeeding by HIV-infected mothers in low-resource countries.

NICHD-funded research has demonstrated that antiretroviral drugs taken by the mother can enter into breast milk, resulting in drug levels being detected in the infant who is exposed to the drug only through breast milk.  The extent of entry into breast milk varies between antiretroviral drugs.  While this may have potential benefits in terms of reducing the risk of HIV transmission, this may also have potential adverse effects for the infant.  The extent and effect of infant drug exposure via breast milk must be well understood to evaluate the benefits and risks of maternal antiretroviral use during breastfeeding.

  • Antiretroviral concentrations in breast-feeding infants of mothers receiving highly active antiretroviral therapy.
    Mirochnick M, Thomas T, Capparelli E, Zeh C, Holland D, Masaba R, Odhiambo P, Fowler MG, Weidle PJ, & Thigpen MC. (2009). Antimicrob Agents Chemother, Mar;53(3), 1170-1176. Epub 2008 Dec 29. [Pub Med ID:  19114673]

Neither infant nor maternal antiretroviral drug use during breastfeeding is completely effective in reducing HIV transmission. Therefore, in the United States, where safe and affordable infant formula is available, the recommendation persists that mothers infected with HIV not breastfeed their infants, even if the mother is receiving antiretroviral therapy. For more information on guidelines for HIV-infected mothers, visit

The NICHD International and Domestic Pediatric and Maternal HIV Clinical Trials Network, in collaboration with the NIAID-funded International Maternal Pediatric Adolescent AIDS Clinical Trials Network, conducts research on use of antiretroviral drugs by pregnant and breastfeeding HIV-infected mothers, including safety, pharmacokinetics as well as potential effects on their infants. 

The latest NICHD Director's Podcast also describes some of the Institute's work related to preventing mother-to-child transmission of HIV. To listen to the podcast, visit

Other Research and Activities Related to Breastfeeding

The NICHD is also involved with various research projects and activities related to breastfeeding and breast milk, including:

  • Neonatal Research Network (NRN): The NRN, supported through the Pregnancy and Perinatology Branch, investigates the safety and efficacy of treatment and management strategies for newborn infants. The NRN has led several of the PP Branch's efforts on breastfeeding and neurodevelopmental outcomes for extremely low birth weight (ELBW) infants and on nutritional management of preterm, low birth weight (LBW), and ELBW infants.
  • Microbicide Trials Network (MTN): MTN researchers, co-funded by the PAMA Branch, are conducting the only studies involving the use of HIV prevention microbicides during pregnancy and breastfeeding to evaluate the safety of their use in women and infants. These studies are critical because women need a product that will be safe and effective to use in all stages of life, including during pregnancy, when the risk of acquiring HIV from an infected partner is particularly high. Because women often continue to use medications when they are pregnant or breastfeeding, knowing whether microbicides are safe to use in this population before they become readily available is also vitally important.
  • Research on the Use of Medications during Pregnancy: Surveys indicate that nearly two-thirds of all pregnant women take four or more drugs during pregnancy and labor, and that medication use frequently continues during breastfeeding. These drugs may be available by prescription or over-the-counter, or they could be categorized as nutritional supplements. The NICHD established the Obstetric and Pediatric Pharmacology (OPP) Branch to promote and coordinate research to improve the safety and efficacy of pharmaceuticals during pregnancy, labor, and breastfeeding.
  • Surgeon General's Call to Action to Support Breastfeeding: The NICHD also participated in activities related to the Surgeon General's Call to Action to Support Breastfeeding. The Call to Action, released in January 2011, identifies ways that families, communities, employers, and health care professionals can increase breastfeeding support and improve breastfeeding rates.

For more information on breastfeeding and on research at the NICHD, select one of the following links:


Originally Posted: August 6, 2012

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