Announcer: From the Eunice Kennedy Shriver National Institute of Child Health and Human Development, part of the National Institutes of Health, welcome to another installment of NICHD Research Perspectives. Your host is the director of the NICHD, Dr. Alan Guttmacher.
Dr. Alan Guttmacher:
Hello, I'm Alan Guttmacher. Thanks for joining us for another in our monthly series of podcasts from the Eunice Kennedy Shriver National Institute of Child Health and Human Development at the National Institutes of Health.
My guests are Dr. Catherine Spong and Dr. Marian Willinger. We'll talk with them about the role that NICHD has played and continues to play in safeguarding infant health. NICHD supports research to ensure that human beings get the best start possible, so all people have the chance to reach their potential, regardless of disease or disability. Today we'll talk about a tremendous problem that interferes with getting people off to a healthy start, the problem of preterm birth. Being born preterm, that is, before the completion of 37 weeks of pregnancy, carries a number of health complications. Preterm infants are at higher risk for dying in the first year of life and also for respiratory problems, life-threatening infections, cerebral palsy, learning disorders, and developmental disabilities. As adults, infants born preterm are at higher risk for type 2 diabetes and heart disease. Preterm infants are also at higher risk than term infants for sudden infant death syndrome, or SIDS. SIDS is the sudden death of an infant under 1 year of age that cannot be explained, even after a complete death scene investigation, autopsy, and review of the infant's health history. SIDS is part of a larger category now referred to as SUID, that's S-U-I-D for sudden unexpected infant death. In addition to SIDS, SUID includes deaths from other causes, like accidental suffocation and entrapment, such as when an infant gets trapped between a mattress and a wall.
Today we'll learn about research to provide the basis for Safe to Sleep, the new NICHD-led campaign to reduce the risk for sudden unexpected infant deaths or providing infants with a safe sleep environment. Our first guest today is Dr. Catherine Spong, NICHD's associate director for extramural research. Before her recent appointment as associate director, Cathy served for many years as the chief of NICHD's Pregnancy and Perinatology Branch, where she oversaw NICHD's research portfolio on preterm birth. Most recently she was an author of the study to investigate the roles of the progesterone compound 17P, as a possible way to prevent preterm birth in certain pregnant women. Before we ask you about that study, Cathy, can you tell us something about the national statistics on preterm birth released earlier this month by our sister federal agency, the National Center for Health Statistics? That includes some encouraging news, didn't it?
Dr. Cathy Spong: Indeed it did. Preterm birth, which is delivery before 37 weeks of gestation, is clearly a public health priority. Nearly half a million children are born preterm in the U.S. each year, and it's associated with many complications both short and long term for the baby. The good news is that for the fifth straight year, the preterm birth rate decreased. It is now at 11.72 percent, which is 2 percent lower than the 2010 rate and 8 percent lower than the rate in 2006. This decreasing preterm birth was both in those who were delivered in the late preterm period, between 34 and 36 weeks, and those in the earlier preterm period, less than 34 weeks; and the decline was also seen in each of the race and ethnic groups, declining 8 to 9 percent for non-Hispanic white and non-Hispanic black infants and 5 percent for Hispanic infants.
Dr. Guttmacher: That's 5 years of progress in terms of the national preterm birth rate is certainly something to celebrate, but of course we still have a long way to go to reduce preterm birth to the much lower levels we'd like to see. In your recent study, you investigated 17P as a preventive for preterm birth in some women, those with a short cervix. Why 17P and why limit the study to only one group of women?
Dr. Spong: So, there are many forms of progestins that have been studied for the prevention of preterm birth. Over the last several decades, trials to prevent preterm birth tended to group together all women who were at risk for preterm birth and test an intervention to see if it was effective. Given that preterm birth is a heterogeneous condition, meaning many different factors lead to preterm birth, this approach was generally not successful. Since then, we've tried this "pieces of the pie" approach, identifying homogeneous groups of women—meaning women having the same underlying risk for the outcome—and testing and intervention. This targeted approach allows better identification of therapies. So this recent trial was undertaken by the NICHD's Maternal-Fetal Medicine Units Network, to look at women in their first pregnancy, who were found to have a short cervix, and evaluative if treatment with a progestin would reduce the risk of preterm birth. In a previous study by this group, women with a prior spontaneous preterm birth who are at very high risk for another preterm birth, were randomized to treatment with 17P or placebo, and the progesterone reduced the risk of preterm birth by about one-third. Only five to six women with a prior preterm birth would need to be treated to prevent one preterm birth. This was a landmark finding. It was the first proven intervention to prevent a subsequent preterm delivery. Now in addition to a prior spontaneous preterm birth, there are other risk factors for preterm birth, such as having short cervix. Other studies found that women with a very short cervix, that at the first or second percentile, progestin seemed to reduce the risk but they included women with other risk factors like those with a prior preterm birth or multi-fetal gestation. So this trial was undertaken to evaluate those women in their first pregnancy who had no other risk factors. It was also designed to look at a larger group of women—those with a short cervical length at the tenth percentile or less. To evaluate the cervical length, you have to do an ultrasound of the cervix, so it was felt that if the intervention worked for women whose cervix was at the tenth percentile or less, then it would be potentially useful to routinely screen all women. The trial did not find a benefit for 17P, so women with a short cervix at the tenth percentile or less, in their first pregnancy, did not have lower rates of preterm birth.
Dr. Guttmacher: I understand that. In what other pieces of the pie—what other groups of women—has 17P been tested?
Dr. Spong: So, the first two we've talked about are those with a prior spontaneous preterm birth where 17P was found to be beneficial and other progestins have been found to be beneficial to reduce the rate of a subsequent preterm birth. Women with a shortened cervical length in the mid-trimester is another at-risk group, the third at-risk group that's been tested are women with multifetal gestations, such as twins or triplets. The MFMU network as well as several other groups internationally have tested for progestins for the prevention of preterm birth in women either with twins or with triplets and also found no benefit in the prevention of preterm birth. Progestins have also been tested in conjunction with other interventions such as omega-3 fatty acids, and also those fatty acids did not reduce further preterm birth beyond that of the progestins.
Dr. Guttmacher: Can you tell us something about the other studies of preterm birth in which NICHD is currently involved and what we might expect to find from them?
Dr. Spong: So the NICHD has a number of ongoing studies on preterm birth that I am really looking forward to the results on. Just to name a few, the Genomics and Proteomics Network on Preterm Birth is applying the advances in proteomics and genomics to the prematurity issue. They've collected cases and controls and are in the midst of analyses to help us understand the genetic and environmental etiologies and the mechanisms of spontaneous preterm birth. There's an ongoing study called New MOM2B, following 10,000 women in pregnancy, that's studying the mechanism and the prediction of preterm birth in women in their first pregnancy. This study is halfway through enrollment. In the Maternal-Fetal Medicine Units Network, there's an ongoing study evaluating the use of antenatal corticosteroids in the late preterm period, those between 34 and 37 weeks, to determine if it's beneficial and improves the outcome for these pregnancies. This trial is also at over 50 percent completed. In addition, there are many other investigator-initiated and basic science research projects that are ongoing to understand and try to prevent prematurity.
Dr. Guttmacher: Cathy, I can see, even if our listeners can't, I can see that Dr. Willinger has a question for you.
Dr. Marian Willinger: Cathy, is there anything that women can do to reduce their chances for giving birth preterm—either when they just find out they're pregnant, or perhaps even when they're thinking about pregnancy?
Dr. Spong: So it's difficult to reduce the risk of preterm birth, in general, because often times we don't know who's going to deliver preterm unless they have one of these risk factors. But I think some things women can do include optimizing their health prior to pregnancy, achieving a normal weight, if possible, getting on a good exercise program, eating a healthy diet, start prenatal vitamins. If they have a medical condition, they should get that under control before attempting pregnancy. They should stop smoking, using illicit drugs, and avoiding alcohol, as all of those have been shown to adversely impact pregnancy outcomes.
Dr. Willinger: Thanks, Cathy.
Dr. Guttmacher: Thanks, Cathy, very much for the entire discussion about preterm birth, which is certainly both a national global priority if we are really going to have to kind of impact we'd like to have in terms of infant mortality and also lifelong disease and health problems. Our next guest today, Dr. Marian Willinger, currently is the acting chief of NICHD's Pregnancy and Perinatology Branch and also oversees our SIDS and SUID-related activities and has for a number of years. Marian, what is now called the Safe to Sleep campaign began as Back to Sleep. Can you tell us about a little about the original Back to Sleep campaign and about the research that led to the campaign's recommendations to place infants to sleep on their backs?
Dr. Willinger: The back to sleep campaign led by NICHD was started in 1994 and was a joint effort of the U.S. Public Health Service, the American Academy of Pediatrics, the SIDS professional and parent organizations. It is a wonderful example of how NICHD mobilized a global community of researchers, health care providers, and parents, to improve the health of our babies. In 1992, the American Academy of Pediatrics recommended that babies be placed on their sides or backs to sleep to reduce the risk for SIDS, and this was based on studies done in England, Australia, and New Zealand. But it was too soon to launch a federal campaign; we needed information from the United States. There was also concern from the U.S. pediatricians that babies would choke on their backs. So we conducted research that showed that babies placed on their backs were not at greater risk for choking and actually were healthier. They had less respiratory and ear infections. We also conducted studies in the U.S. showing that babies placed on their back to sleep had the lowest risk of SIDS, compared to babies placed on their sides or stomach because the side is a very unstable position and babies can roll to their stomach. This led to a recommendation that back is best. We also conducted surveys to show that providers and caregivers were not implementing the American Academy recommendation, and so a consensus was reached that a national campaign was needed. Since then, these annual surveys have shown that between 1994 and 2000, as more babies were placed on their backs, the SIDS rate in the U.S. was cut in half and it has remained half of the rate since 1992.
Dr. Guttmacher: Marian, that really is just an incredible amount of progress. Before we talk more about the research, could you briefly review for us, based on what we now know, how and under what circumstances parents and caregivers should place infants to sleep?
Dr. Willinger: During all sleep time—nap time and night time—babies should be placed on their backs in a safety-approved crib or bassinet. Their sleep place should have a firm mattress and fitted sheet, with no blankets under them or pillows, no bumpers, quilts, or comforters in their crib. Babies should not be placed to sleep on a couch or an adult bed: these are very risky places for a baby to sleep. Bed sharing also is not recommended. If parents wish to bring their babies into bed to cuddle or to breastfeed, as soon as they or the baby gets sleepy, the baby should be placed in his or her own crib or bassinet.
Dr. Guttmacher: So the original Back to Sleep campaign began in 1994. It certainly appears to have been incredibly successful, as you mentioned, since the campaign began the rate of SIDS deaths in the U.S. has gone down by more than half. We fast-forward now to 2012, we still stress placing infants to sleep on their backs, but we've revamped Back to Sleep into Safe to Sleep, to include what we've learned about the influence of the sleep environment and sleep-related, sudden unexpected infant death. Can you tell us what the health behavior studies have informed us about infant sleep environment?
Dr. Willinger: Well, our studies of SIDS risk factors in the United States have shown that in addition to sleeping on the stomach, soft bedding in the crib (and I mean over the baby or under the baby) or pillows, or sharing a bed with adults or children, increases the risk for SIDS. The Consumer Product Safety Commission collected data that these conditions are also associated with babies who die from overlay, entrapment (for example, between the mattress and a wall or the mattress and a bed frame), or suffocation. So accidental deaths in the infant sleep environment share many risk factors with SIDS. While our Back to Sleep campaign materials recommended that soft bedding be removed from the baby's crib and that babies not bed-share, our surveys of infant care practices have shown that many caregivers are not following these recommendations. So a Safe to Sleep campaign, which targets risk factors for both SIDS and accidental deaths in the infant sleep environment, is needed.
Dr. Guttmacher: You've already said something about people's attitudes. It's easy to understand. I mean, some of these changes-- like avoiding soft bedding-- fly in the face of what many of us were raised to believe was nice for babies, etc. Can you tell us something more about how people are accepting the campaign's current advice?
Dr. Willinger: Well, most people are accepting the advice and we hope with the new approaches used for this campaign, all caregivers will. We've learned from our research that parents and other caregivers are most concerned about the baby's safety and comfort. These are the reasons they do not follow the recommendations. They are misguided because, in reality, they are increasing the chance that a baby will die due to SIDS or overlay or entrapment. So the Safe to Sleep campaign is providing specifics on how to make the sleep environment safe to reduce the risk of these deaths and to dispel the myths about choking. Our studies have also shown that the more sources that give the recommendations to the mother or other caregiver, the more likely they will accept and follow the recommendations. So the new campaign is continuing efforts to work with specific high-risk communities in a grassroots format with a train-the-trainer program and to educate all health providers including nurses and pharmacists. We have also cemented our collaborations with all the federal agencies that are responsible for family health, so that we are all promoting Safe to Sleep.
Dr. Guttmacher: Thank you very much, Marian. As someone who's expecting our first grandchild in a few months, I'll make sure that we take that advice to heart and make sure that other family members who will be taking care of the baby at times will also be aware of it.
Dr. Spong: Marian, if I may, there's two questions I have for you. First, do we have any reliable estimates on the proportion of accidental sleep-related deaths versus SIDS deaths?
Dr. Willinger: Well, the Centers for Disease Control and Prevention have been collecting these deaths every year; and for years 2003 and 2004 combined, there were 4,408 SIDS deaths and 931 accidental suffocation and strangulation in bed deaths. So there are about five times as many SIDS deaths as suffocation deaths.
Dr. Spong: And there have been some studies on brain chemistry of the SIDS cases. What have we learned from those?
Dr. Willinger: We have learned that when the chemistry of the brain stem is examined, the majority of SIDS cases have abnormalities in a network of brain cells that control the babies' arousal response to the amount of carbon dioxide they breathe, their body temperature, their blood pressure—basically, the baby's response to life-threatening conditions that might arise in the sleep environment. In the SIDS babies, the brain cells in this network have a reduced amount of serotonin and a reduced amount of receptors that actually use serotonin, a chemical the brain cells use to communicate with and function properly. It also appears that this network of brain cells is underdeveloped. Unfortunately, we are not at this stage yet that we can use this information to identify babies with the brain defect before they die. But we have a study ongoing right now, which is following babies from pregnancy through infancy, where we are learning more about the physiology so that we can develop diagnostic tools to predict those babies with the abnormalities.
Dr. Spong: So this means we actually have a reason for why some of these babies die: there is something actually abnormal in the baby's brain stem development.
Dr. Willinger: Yes, we really believe that this is the case, and we also have some very exciting animal model research where we can actually create animals with this deficit and show that they mimic the SIDS phenotype.
Dr. Guttmacher: Marian, that's certainly a very useful understanding of the biology that leads to SIDS very frequently. But there's no way that we can tell for a given infant ahead of time whether they might have one of these variations. So that's the reason we need to treat all children as though they might be at risk.
Dr. Willinger: Absolutely. And that was one of big things that we discussed when we initiated the Back to Sleep campaign and why it was so important for us to demonstrate that there really was no risk for putting a baby on their back, that this was really a safe thing to do and a relatively easy thing to do.
Dr. Guttmacher: That brings us to the end of our podcast for this month. I'd like to thank both Dr. Willinger and Dr. Spong for joining us today and for sharing with us some of the research in their areas. I'd also like to thank our podcast listeners for joining in and for your interest in our work at NICHD.
For more information on any of today's topics and many related topics, visit www.nichd.nih.gov. That's www.nichd.nih.gov.
I'm Alan Guttmacher, and I hope you will join us for more NICHD podcasts as we post them on our website each month.
Announcer: This has been NICHD Research Perspectives, a monthly podcast series hosted by Dr. Alan Guttmacher. To listen to previous installments, visit Research Perspectives . If you have any questions or comments, please email NICHDInformationResourceCenter@mail.nih.gov.
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