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New Cochrane Review: Delayed Cord Clamping Likely Beneficial for Healthy Term Newborns

July 25th, 2013 by avatar

By Mark Sloan, M.D.

Last fall, Dr. Mark Sloan wrote an extremely well-received post on Science & Sensibility, Common Objections to Delayed Cord Clamping; What’s the Evidence Say? that both professionals and consumers could use to understand and discuss the benefits of delayed cord clamping. From that post, we read that early cord clamping is an intervention that needs to change.  Yet, early cord clamping is still observed in L&D rooms across the United States, despite the mounting evidence for waiting at least 1-3 minutes before clamping occurs.  A new Cochrane review was just released in July, 2013, and I am grateful to Dr. Sloan for summarizing this review and sharing the  new information on this topic. – Sharon Muza, Community Manager, Science & Sensibility

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flickr.com/photos/lovemybunnies/4740682244/

A new Cochrane review of the timing of cord clamping in healthy term neonates was released earlier this month: Effect of timing of umbilical cord clamping of term infants on mother and baby outcomes. It’s an update of a 2009 review on the subject, and the language is more pro-delayed cord clamping (ie, clamping the cord at 1-3 minutes after birth) this time around. Here’s an excerpt from the Author’s Conclusions:

 “A more liberal approach to delaying clamping of the umbilical cord in healthy term infants appears to be warranted, particularly in light of growing evidence that delayed cord clamping increases early haemoglobin concentrations and iron stores in infants. Delayed cord clamping is likely to be beneficial as long as access to treatment for jaundice requiring phototherapy is available.”

To understand why this change in emphasis since the 2009 Cochrane review is important, let’s first look at why the timing of cord clamping is important to newborns, how current obstetric practice came to be, and what the Cochrane review did (and didn’t) find. 

A brief physiology review

At term, roughly 1/3 of a fetus’s blood supply resides in the placenta. In the course of labor and delivery, much of that blood is transfused from the placenta into the fetus/newborn, driven by the force of uterine contractions. That transfusion continues beyond the moment of birth; if left undisturbed for 1 to 3 minutes, the placenta will deliver about three additional ounces of blood to the newborn.

That may not sound like much, but three ounces of blood is equivalent to a three month supply of iron for the newborn. Iron is critical to brain growth and development; iron deficiency is a known cause of cognitive and social-emotional deficits in infants, which may be permanent. As breast milk alone may not supply a baby with all the iron he or she needs, it’s that additional iron that makes delayed cord clamping (DCC) so important. 

A brief history of cord clamping

Until the relatively recent past, the umbilical cord was generally allowed to stop pulsating before it was cut and tied off. Aristotle and Hippocrates, among many other medical and science writers, wrote approvingly of the practice. The first mention of early cord clamping (ECC)—cutting the cord before pulsation has ceased—is found in the 1600s, when management of the third stage of labor changed with the rise of male midwives, flat-on-the-back birthing practices, and forceps. 

Though ECC gained in popularity, controversy dogged the practice from the beginning. To give just one example, the prominent British physician Erasmus Darwin (Charles’s grandfather) condemned the practice, declaring in 1801 that early cord clamping was “a very injurious thing” that left babies “much weaker than [they] ought to be.” 

Despite ongoing objections, ECC became the obstetrical standard of care in the mid-1960s, promoted primarily as a tool to prevent maternal postpartum hemorrhage (PPH). Though subsequent research has shown that ECC is of no benefit in postpartum hemorrhage (PPH) prevention, the practice remains a firmly entrenched part of obstetrical care in the U.S. 

What did the 2013 Cochrane review find?

The review found that DCC babies had significantly higher body iron stores than ECC babies, an increase that persisted for months.

What didn’t the Cochrane review find?

Maternal adverse outcomes: The review found no significant ECC-versus-DCC differences in any maternal outcomes, including postpartum hemorrhage, length of the third stage of labor, need for blood transfusion, and need for manual removal of the placenta.

Neonatal adverse outcomes: Similarly, with the single exception of a slight increase in the need for phototherapy to treat hyperbilirubinemia (discussed below), there were no significant differences between ECC and DCC babies in neonatal outcomes such as mortality, Apgar scores < 7 at five minutes, need for resuscitation, NICU admission, respiratory distress, polycythemia, and clinical jaundice.

The apparent association between DCC and an increased need for phototherapy is a bit controversial. As pointed out by Dr. Judith Mercer, an expert on the benefits of delayed clamping, this concern is based largely on a single unpublished 1996 study performed by one of the Cochrane review’s authors (McDonald).  McDonald’s study is one of only two of the nearly forty studies considered for inclusion in the current review that includes unpublished data; when that data is removed, the difference between groups loses significance.   

Of note, the two studies added since the 2009 review found no association between delayed clamping and hyperbilirubinemia requiring phototherapy (Al-Tawil 2012, Andersson 2011). It should also be pointed out that none of the babies in these studies was harmed by hyperbilirubinemia. All recovered completely; there were no cases of kernicterus—brain damage caused by severe neonatal jaundice.

Whatever the case regarding delayed clamping and phototherapy, there’s no doubt that iron deficiency in infancy can lead to permanent cognitive and social-emotional deficits. The global benefits of increased iron stores during a critical period of brain development would seem to outweigh that concern.

The bottom line

For healthy term babies, a delay of 1-3 minutes before cord clamping has been shown to increase neonatal iron stores at a critical period of brain development, with virtually no risk of harm to mother and baby. Conversely, there is no convincing argument in support of clamping the umbilical cord before a minute of age.

Given that ECC has been shown to have no impact on maternal PPH, and that it offers no demonstrable benefit to healthy term newborns (and may in fact be harmful, by reducing body iron stores during a critical period of brain development), the question isn’t “Why switch to delayed cord clamping?” It’s this: “Why continue to intervene?”

Will obstetric practice change? Not immediately, if the recent Huffington Post comments of Dr. Jeffrey Ecker, ACOG chair of obstetric practice, are any indication: 

“Over time, I believe we’ll see an evolution in practice with appropriate women and babies — babies that don’t otherwise need immediate attention,” Ecker said. “I don’t think it is all going to change in a year. But in five, 10 years, we’ll look back and say, ‘Boy, this is different.’”

The best way to speed up that process is for pregnant women and providers of maternity care services to press their local hospitals for change now.

References

Al-Tawil, M. M., Abdel-Aal, M. R., & Kaddah, M. A. (2012). A randomized controlled trial on delayed cord clamping and iron status at 3–5 months in term neonates held at the level of maternal pelvis. Journal of Neonatal-Perinatal Medicine5(4), 319-326.

Andersson, O., Hellström-Westas, L., Andersson, D., & Domellöf, M. (2011). Effect of delayed versus early umbilical cord clamping on neonatal outcomes and iron status at 4 months: a randomised controlled trial. BMJ: British Medical Journal343.

California WIC Association and the UC Davis Human Lactation Center. (2012) Maternity Care Matters; Overcoming Barriers to Breastfeeding. A Policy Update on California Breastfeeding and Hospital Performance. Retrieved from http://calwic.org/storage/restricted/hospitalreport/Maternity%20Care%20Matters_2012.pdf

McDonald, S. J., Middleton, P., Dowswell, T., & Morris, P. S. (2013). Effect of timing of umbilical cord clamping of term infants on mother and baby outcomes. Health.

Pearson, Catherine. “Cord Clamping: How Delaying Helps Babies.” The Huffington Post. TheHuffingtonPost.com, 11 July 2013. Web. 24 July 2013.

About Mark Sloan, MD

Mark Sloan has been a pediatrician and a Fellow of the American Academy of Pediatrics for more than 25 years. Since 1982, he has practiced with the Permanente Medical Group in Sacramento and Santa Rosa, California, where he was Chief of Pediatrics from 1997 to 2002. He is an Assistant Clinical Professor in the Department of Community and Family Medicine at the University of California, San Francisco. Dr. Sloan’s first book, Birth Day: A Pediatrician Explores the Science, the History and the Wonder of Childbirth was published in 2009 by Ballantine BooksHis writing has appeared in the Chicago Tribune, the San Francisco Chronicle, the San Francisco Examiner, and Notre Dame Magazine, among other publications.  Dr. Sloan can be reached through his blog.

 

Babies, Childbirth Education, Delayed Cord Clamping, Do No Harm, Evidence Based Medicine, Guest Posts, informed Consent, Medical Interventions, New Research, Newborns, Practice Guidelines, Research, Third Stage , , , , , , , , ,

Common Objections to Delayed Cord Clamping – What’s The Evidence Say?

November 13th, 2012 by avatar

by Mark Sloan M.D.

Today’s guest post is written by Dr. Mark Sloan, pediatrician and author of Birth Day: A Pediatrician Explores the Science, the History and the Wonder of Childbirth.  Dr. Sloan shares information and current research on delayed cord clamping after birth, in a helpful Q&A style format that consumers and professionals can use to discuss this important topic.

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photo credit pattiramos.com

Many maternity care providers continue to clamp the umbilical cord immediately after an uncomplicated vaginal birth, even though the significant neonatal benefits of delayed cord clamping (usually defined as 2 to 3 minutes after birth) are now well known.

In some cases this continued practice is due to a misunderstanding of placental physiology in the first few minutes after birth. In others, human nature plays a role: We are often reluctant to change the way we were taught to do things, even in the face of clear evidence that contradicts that teaching.

Though there is no strong scientific support for immediate cord clamping (ICC), entrenched medical habits can be glacially slow in changing. Here are some often-heard objections to delayed cord clamping (DCC), and how an advocate for delayed clamping might respond to them:

1) I have a very busy practice. DCC takes too much time!

Not really, especially when you consider the benefits. Nearly one-third of a baby’s total blood volume resides in the placenta at birth. Half of that blood is transfused into the baby by 1 minute of age. By 3 minutes, more than 90% of the transfusion is complete. (1)

 2) Immediate clamping helps prevent severe postpartum hemorrhage.

There is no convincing evidence to support this view. Several large studies, including a 2009 Cochrane review of 5 trials involving more than 2,200 women, have found no significant difference between ICC and DCC in terms of postpartum hemorrhage or severe postpartum hemorrhage. (2-6, 10)

 3) A healthy, term baby doesn’t get much benefit from delayed clamping.

Though this is a commonly held belief, it’s definitely untrue.

Whether a fetus is premature or full term, approximately one-third of its total blood volume resides in the placenta. This is equal to the volume of blood that will be needed to fully perfuse the fetal lungs, liver, and kidneys at birth.

In addition to the benefits that come with adequate iron stores (see below), babies whose cords are clamped at 2 to 3 minutes—and thus, who have an increased total blood volume compared with their immediately-clamped peers—have a smoother cardiopulmonary transition at birth.

A third benefit: stem cells, which play an essential role in the development of the immune, respiratory, cardiovascular, and central nervous systems, among many other functions. The concentration of stem cells in fetal blood is higher than at any other time of life. ICC leaves nearly one-third of these critical cells in the placenta. (1,3,4,6-10)

Unclamped cord over the course of 15 minutes.
photo nurturingheartsbirthservices.com

 4) Okay, so delayed clamping means a baby gets more blood and more iron. But iron deficiency isn’t really a problem in first-world countries, right?

Wrong. At least 10% of the general U.S. toddler population (1-3 years of age) is iron deficient, with the prevalence rising well above 20% in selected ethnic and socioeconomic populations.

Immediate cord clamping is only one of many factors that contribute to iron deficiency in early childhood. But babies who start out life low on iron have a very difficult time catching up. Delayed cord clamping provides a baby with as much as a 4- to 6-month supply of iron. (1,3,6-10)

 5) Doesn’t iron deficiency just make kids tired?

Iron deficiency does much more damage than that. Early infancy is a time of rapid brain growth and development, and iron is essential to that process. Studies of infants with iron deficiency have found specific deficits in cognitive processing (including attention and memory) which may lead to permanently decreased intellectual functioning. Making matters even worse, children with severe iron deficiency often exhibit “emotional dulling”—difficulty engaging with caretakers and their environment—which can lead to long-lasting social-emotional deficits. For many reasons, early infancy is a particularly bad time to be low on iron. (1,11)

 6) Don’t babies get plenty of iron from breast milk? 

Unfortunately, no. While breast milk contains a remarkable array of healthful components, a high concentration of iron isn’t one of them. This most likely has to do with maternal recovery from childbirth. A recuperating mother has her own urgent iron needs; replacing the blood typically lost in childbirth takes a lot of it. Nature intends babies to get most of the iron they’ll need for their early development from the placental blood reservoir, rather than from mother, and so comparatively little iron goes into breast milk.  (3,7)

 7) But the baby can lose significant blood volume back into the placenta (aka “backflow bleeding”) if clamping is delayed.

This is extremely unlikely in an uncomplicated birth. With some brief exceptions (e.g., between uterine contractions, or when a baby bears down during crying), blood flow immediately after birth is primarily one-way, from placenta to baby. Here’s a brief explanation of why this is true:

In a process that begins during labor and accelerates as the newborn begins to cry, the pulmonary blood vessels, which receive very little blood flow during pregnancy, open and fill. This relatively sudden change causes the newborn’s blood pressure to fall below the pressure in the placenta. Placental blood, driven by strong uterine contractions, follows the pressure gradient and flows through the umbilical vein into the baby.

As the newborn’s oxygen saturation increases, the umbilical arteries close, which stops nearly all blood flow from baby to placenta. The umbilical vein, which isn’t sensitive to oxygen, remains open somewhat longer, allowing a final bit of blood to flow from placenta to baby before it, too, closes.

The lack of significant “backflow bleeding” is confirmed by the fact that DCC results in ~ 30% greater neonatal blood volume than does ICC.  (1,12)

8) DCC can lead to dangerously high levels of neonatal jaundice.

Since bilirubin, the source of neonatal jaundice, originates in red blood cells, it seems logical that the increased blood volume associated with delayed clamping could lead to severe hyperbilirubinemia.

Yet while some studies have demonstrated mildly increased bilirubin levels in DCC babies in the first few days postpartum, most have found no significant difference between DCC and ICC.

This seeming paradox—relatively stable bilirubin levels in the face of substantially increased blood volume—may have to do with increased blood flow to the neonatal liver that comes with the higher total blood volume associated with DCC. Yes, more blood means more bilirubin, which in turn could mean more jaundice, but better blood flow allows the liver to process bilirubin more efficiently.  (3,4,6,7,9,10)

 9) Delayed clamping can lead to neonatal hyperviscocity—“thick blood” that can cause kidney damage and strokes.

DCC can lead to a somewhat higher neonatal hematocrit than ICC, which isn’t surprising given the additional blood volume. Yet, despite fears of thicker blood “sludging” in organs like the brain and kidneys, no studies have demonstrated this to be the case from DCC alone. (4,6,9,10)

 10) You can’t have both the benefits of DCC and immediate skin-to-skin contact. If you place a newborn on his mother’s abdomen (i.e., above the level of the placenta), gravity will reduce the flow of blood from placenta to baby.

Gravity does matter, but mainly in terms of the speed of the placental transfusion. A baby held below the level of the placenta will receive a full transfusion in about 3 minutes; one held above the placenta (e.g., a baby in immediate skin-to-skin contact) will also receive a full transfusion—it just takes a little longer (about 5 minutes). (1,13)

 11) But what if the baby needs resuscitation? Isn’t it best to hand her over to the pediatrician immediately?

One of the first things a truly sick baby in the NICU is going to receive is fluid support—often as a 20 to 40 ml/kg bolus of normal saline or blood. Yet that is exactly what’s left behind in the placenta with ICC—about 30 ml/kg of whole blood. There is considerable evidence that sick babies, both term and preterm, have better outcomes with DCC. It’s better to let nature do its own transfusing. (14-16)

Summary: 

Delayed cord clamping promotes a healthy neonatal cardiopulmonary transition, prevents iron deficiency at a critical time in brain development, provides the newborn with a rich supply of stem cells, and helps sick neonates achieve better outcomes—all with little apparent risk to mother or baby. The evidence of benefit from DCC is so compelling that the burden of proof must now lie with those who wish to continue the practice of immediate clamping, rather than with those who prefer—as nature intended—to wait.

What do you tell your patients, students and clients about delayed cord clamping?  Do you have a favorite resource or two that you like to share?  What are the community standards around delayed cord clamping in your community?  Are health care providers discussing this with their patients?  Do they have recommendations one way or another that you are hearing?  Please join in the discussion.- SM

References

1) Mercer JS, Erickson-Owens DA. Rethinking placental transfusion and cord clamping issues. Journal of Perinatal & Neonatal Nursing. July/September 2012 26:3; 202–217 doi: 10.1097/JPN.0b013e31825d2d9a

2) Andersson O, Hellstrom-Westas L, Andersson D, et al. Effects of delayed compared with early umbilical cord clamping on maternal postpartum hemorrhage and cord blood gas sampling: a randomized trial. Acta Obstetricia et Gynecologica Scandinavica. Article first published online: 17 Oct, 2012. DOI: 10.1111/j.1600-0412.2012.01530.x

3) Chaparro, CM. Timing of umbilical cord clamping: effect on iron endowment of the newborn and later iron status. Nutrition Reviews. Volume 69, Issue Supplement s1, pages S30–S36, November 2011.

4) Ceriani Cernadas JM, Carroli G, Pellegrini L, et.al. The Effect of Timing of Cord Clamping on Neonatal Venous Hematocrit Values and Clinical Outcome at Term: A Randomized, Controlled Trial. Pediatrics. Vol. 117 No. 4 April 1, 2006 pp. e779 -e786 (2,3 8,9(doi: 10.1542/peds.2005-1156). Published online March 27, 2006.

5) WHO. Department of Making Pregnancy Safer. WHO recommendations for the prevention of postpartum haemorrhage. Geneva: World Health Organization, 2007.

6) McDonald SJ, Middleton P. Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes. Cochrane Database of Systematic Reviews 2008, Issue 2. Art. No.: CD004074. DOI:10.1002/14651858.CD004074.pub2.

7) Andersson O, Hellstrom-Westas L, Andersson D, Domellof M. Effect of delayed versus early umbilical cord clamping on neonatal outcomes and iron status at 4 months: a randomised controlled trial. British Medical Journal. 2011; 343: d7157. Published online 2011 November 15. doi:  10.1136/bmj.d7157

8) Ceriani Cernadas JM, Carroli G, Pellegrini L, et.al. The effect of early and delayed umbilical cord clamping on ferritin levels in term infants at six months of life: a randomized, control trial. Arch Argent Pediatr. 2010; 108:201-208.

9) Hutton EK, Hassan ES. Late vs early clamping of the umbilical cord in full-term neonates: systematic review and meta-analysis of controlled trials. JAMA. 2007 Mar 21;297(11):1241-52.

10) McDonald SJ, Middleton P. Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes. Cochrane Database of Systematic Reviews 2008, Issue 2. Art. No.: CD004074. DOI:10.1002/14651858.CD004074.pub2.

11) Carter RC, Jacobson JL, Burden MJ, et al. Iron deficiency anemia and cognitive function in infancy. Pediatrics. 2010; 126:2 pp e427-e434 (doi: 10.1542/peds.2009-2097).

12) Mercer JS, Skovgaard R. Neonatal Transitional Physiology: A New Paradigm. J Perinat Neonat Nursing 2002; 15(4) 56-75

13) Yao AC, Lind J. Effect of gravity on placental transfusion. Lancet. 1969; 2:505-508.

14) Mercer JS, Vohr BR, Erickson-Owens DA, et al. Seven-month developmental outcomes of very low-birth-weight infants enrolled in a randomized controlled trial of delayed versus immediate cord clamping. J Perinatol. 2010; 30:11-16.

15) Kinmond S, Aitchison TC, Holland BM, et al. Umbilical cord clamping and preterm infants: a randomized trial. British Medical Journal. 1993; 306:172-175.

16) Rabe H, Wacker, A, Hulskamp G, et al. A randomized controlled trial of delayed cord-clamping in very low-birth-weight preterm infants Eur J Pediatr. 2000; 159:775-777.

About Mark Sloan, M.D.

Mark Sloan has been a pediatrician and a Fellow of the American Academy of Pediatrics for more than 25 years. Since 1982, he has practiced with the Permanente Medical Group in Sacramento and Santa Rosa, California, where he was Chief of Pediatrics from 1997 to 2002. He is an Assistant Clinical Professor in the Department of Community and Family Medicine at the University of California, San Francisco. Dr. Sloan’s first book, Birth Day: A Pediatrician Explores the Science, the History and the Wonder of Childbirth was published in 2009 by Ballantine BooksHis writing has appeared in the Chicago Tribune, the San Francisco Chronicle, the San Francisco Examiner, and Notre Dame Magazine, among other publications.  Dr. Sloan can be reached through his blog.

 

American Academy of Pediatrics, Delayed Cord Clamping, Do No Harm, Evidence Based Medicine, Healthy Birth Practices, Healthy Care Practices, informed Consent, Medical Interventions, Newborns, Research, Third Stage, Uncategorized , , , , , , , , , ,

Unintended Consequences: Cesarean Section, The Gut Microbiota, and Child Health

July 12th, 2012 by avatar

Today’s guest post is written by Dr. Mark Sloan, pediatrician and author of Birth Day: A Pediatrician Explores the Science, the History and the Wonder of Childbirth.  Dr. Sloan takes a look at impact of cesarean birth on normal gut bacteria.  – SM

When I first learned some years ago that cesarean section was associated with an increased risk of childhood asthma and eczema, I eagerly awaited the rest of the story. What could the link possibly be? Epidurals? Anesthetics? Antibiotics? Something strange and exotic was afoot, I was certain.

Imagine my surprise, then, when a growing body of evidence pointed to an unexpected source: the newborn gastrointestinal tract and the microorganisms that live there.

How might intestinal bacteria play such a major role in the health and well-being of newborns and children? The answer lies in an ancient, mutually beneficial relationship between humans and bacteria, one that modern birth technology has dramatically altered.

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Creative Commons photo by Eric Erbe, Colorization by Christopher Pooley. USDA

“Microbiota” is the term used to describe the community of microorganisms—bacteria, viruses, and fungi—that normally live in or on a given organ in the body. There’s a unique microbiota that inhabits the mouth, for example, another that lives on the skin, and still another that populates the intestine, or gut. Given an intestinal surface area of about 2,700 square feet—more or less the size of a tennis court—the microbiota inhabiting the gut is the largest and most diverse in the body.

How large and diverse? The gut microbiota contains roughly one quadrillion cells—at least ten times as many cells as does the human body itself. More than 1,000 bacterial species having been identified to date, with unknown numbers yet to be discovered.

How do all those bacteria get there? The fetal intestine, in the absence of congenital infection, is sterile in utero. The bacteria that come to colonize the bowel are acquired during birth and shortly afterwards, a process that is very much influenced by how a baby is born.

The gut microbiota and mode of delivery

In vaginally-born babies, the bacteria destined for the gut microbiota originate primarily in the maternal birth canal and rectum. Once these bacteria are swallowed by the newborn, they travel through the stomach and colonize the upper and lower intestine, a complicated process that evolves rapidly.

Infants born by cesarean section—particularly cesareans performed before labor begins—don’t encounter the bacteria of the birth canal and maternal rectum. (If a cesarean is performed during labor the infant may be exposed to these bacteria, but to a lesser degree than in vaginal birth.) Instead, bacteria from the skin and hospital environment quickly populate the bowel. As a result, the bacteria inhabiting the lower intestine following a cesarean birth can differ significantly from those found in the vaginally-born baby.

Whatever the mode of delivery, a core gut microbiota is well established within a few weeks of life and persists largely intact into adulthood. A less stable peripheral microbiota—one that is more sensitive to changes in diet and environmental factors, like antibiotics—is created as well. Between one and two years of age, when weaning from breast milk typically leads to a diet lower in fat and higher in carbohydrates, the gut microbiota takes on its final, mature profile.

Development of the newborn immune system 

The dramatic first steps in immune system development take place at the same time the core microbiota is being formed, and the gut bacteria play a key role in that process.

In the hours and days following birth, the newly-arrived gut bacteria stimulate the newborn to produce white blood cells and other immune system components, including antibodies directed at unwelcome, disease-causing microorganisms. The bacteria of the microbiota also “teach” the newborn’s immune system to tolerate their own presence—to differentiate bacterial friend from foe, in other words.

In a cesarean birth the fledgling immune system is confronted with unfamiliar, often hostile bacteria—including Clostridium difficile, a particularly troublesome hospital-acquired bug. In addition, the healthy probiotic bacteria associated with vaginal birth (e.g., lactobacillus) arrive later and in lower numbers. These changes in the composition of the normal gut microbiota occur during a critical time in immune system development.

The cesarean-asthma theory (in a nutshell) 

Here’s how cesareans and asthma are likely connected:

Creative Commons photo by hemangi28

Humans evolved right along with the gut microbiota normally acquired during vaginal birth. When the composition of the microbiota is imbalanced, or unusual germs like Clostridium difficile appear, the immune system doesn’t like it. A low-grade, long-lasting inflammatory response directed at these intruders begins at birth, leading to a kind of weakness and “leakiness” of the intestinal lining. Proteins and carbohydrates that normally would not be absorbed from the intestinal contents—including large, incompletely digested food molecules—make their way into the infant’s bloodstream.

To make a very long story short, inflammation and the abnormal processing of food that results appear to increase the risk of asthma and eczema—and diabetes, obesity, and other chronic conditions—later in life.

* * *

Normalizing the post-cesarean gut microbiota

 Reducing the cesarean rate is an obvious best practice in promoting a healthy gut microbiota. But there will always be a need for cesarean section, and so researchers are starting to focus on “normalization” of the gut microbiota of cesarean-born babies. Although there are as yet no proven therapies, here are some possibilities:

  • Probiotics. Though administering healthful probiotic bacteria to correct an imbalanced microbiota makes intuitive sense, studies to date have been disappointing, with only minor, short-lived changes changes to the gut microbiota. However, research into “good” bacteria and how they become established in the intestine is active and ongoing.
  • Direct transfer of maternal secretions. Placing maternal vaginal and rectal material into the newborn’s mouth has been proposed—more or less mimicking natural colonization—but to date there are no published studies to support the practice.
  • Fecal transplantation. Direct transfer of fecal material from healthy adults into the gastrointestinal tracts of people suffering from Clostridium difficile infections has shown promise. Could healthy parents serve as “donors” for their babies? Applying such technology to otherwise healthy newborns is highly impractical at present, to say the least. Still, refinements may someday make this a viable option.

Conclusion

A cesarean section doesn’t automatically condemn a child to a lifetime of asthma or eczema, just as a vaginal birth isn’t a guarantee of perfect health. But cesarean birth, by altering normal gut microbiota and immune system development, does appear to moderately increase the risk of these and other chronic health conditions. A woman who has the option of choosing her mode of delivery should add this to the many other factors she must weigh in deciding how her baby will be born.

Childbirth educators and other birth professionals, when you speak to your classes or clients about the benefits and risks of cesarean section, do you mention this information.  What do you think about this connection?  What should your students know about how to minimize the impact of cesarean on the future potential health of their children?  Please share your thoughts on the comment section,- SM

 Selected references:

1)    Effects of mode of delivery on gut microbiota composition 

Biasucci G, Rubini M, Riboni S, et al (2010). Mode of delivery affects the bacterial community in the newborn gut. Early Human Development 86:S13-S15

Penders J, Tjhijs C, Vink C, et al (2006). Factors influencing the composition of the intestinal microbiota in early infancy. Pediatrics 118(2):511-521.

Salimen S, Gibson GR, McCartney AL (2004). Influence of mode of delivery on gut microbiota in seven year old children. Gut 53:1388-1389.

2)    Development of the newborn immune system

Huurre A, et al (2008). Mode of delivery: Effects on gut microbiota and humoral immunity. Neonatology 93:236-240.

Johnson C, Versalovic J (2012). The human microbiome and its potential importance to pediatrics.  Pediatrics (published online April 2, 2012; DOI: 10.1542/peds2011-2736).

Vael C, Desager, K (2009). The importance of the development of the intestinal microbiota in infancy. Current Opinion in Pediatrics 21(6):794-800

3)    Cesarean birth, gut microbiota, and asthma/atopic disease

Azad M, Korzyrkyj A (2012). Perinatal programming of asthma: The role of the gut microbiota. Clinical and Developmental Immunology Volume 2012; Article ID 932072; doi:10.1155/2012/932072

Thanvagnanam S, Fleming J, Bromley A, et al (2008). A meta-analysis of the association between caesarean section and childhood asthma. Clinical & Experimental Allergy 38(4): 629-633.

van Nimwegen F, Penders J, Stobberingh E, et al (2011). Mode and place of delivery, gastrointestinal microbiota, and their influence on asthma and atopy. Journal of Allergy and Clinical Immunology 128(5):948-955.e3

About Mark Sloan, M.D.

Mark Sloan has been a pediatrician and a Fellow of the American Academy of Pediatrics for more than 25 years. Since 1982, he has practiced with the Permanente Medical Group in Sacramento and Santa Rosa, California, where he was Chief of Pediatrics from 1997 to 2002. He is an Assistant Clinical Professor in the Department of Community and Family Medicine at the University of California, San Francisco. Dr. Sloan’s first book, Birth Day: A Pediatrician Explores the Science, the History and the Wonder of Childbirth was published in 2009 by Ballantine BooksHis writing has appeared in the Chicago Tribune, the San Francisco Chronicle, the San Francisco Examiner, and Notre Dame Magazine, among other publications.  Dr. Sloan can be reached through his blog.

 

 

Babies, Cesarean Birth, Childbirth Education, Evidence Based Medicine, Guest Posts, Healthy Care Practices, informed Consent, Newborns, Practice Guidelines, Push for Your Baby, Research, Uncategorized , , , , , , , ,

Delivery By Cesarean Section And Risk Of Obesity In Preschool Age Children; Research Review

June 21st, 2012 by avatar

Today’s guest post is written by Dr. Mark Sloan, pediatrician and author of Birth Day: A Pediatrician Explores the Science, the History and the Wonder of Childbirth.  Dr. Sloan takes a look at the study released in May, 2012 examing the relationship between Cesarean deliveries and obesity in preschoolers. – SM

I don’t recall learning much about childhood obesity in my early-1980s pediatric residency. This was partly due to the fact that obesity wasn’t all that common—only about 7% of kids fell into that category at the time—and partly because the solution seemed obvious, and not quite worthy of medical attention. “Join a baseball team, kid,” my senior resident once told an overweight boy with asthma. “And you,” he said, pointing an accusatory finger at the boy’s mother. “Stop buying cookies, okay?”

Creative Commons photo by LouLou-Nico

One thing I did learn a lot about in residency, though, was cesarean section. The U.S. cesarean rate topped 20% for the first time, up from 6% just a decade earlier.  I spent a steadily increasing amount of time in operating rooms, waiting for an obstetrician to hand me a baby.

We all thought the rise in cesareans was a good thing—think of the lives saved, the brain damage avoided, we told ourselves.  If anyone had suggested cesarean birth might be creating long-term health problems for those “saved” babies, we would have scoffed. And had anyone suggested that it might lead to a lifetime of obesity, we’d have laughed them right out of the hospital.

But here we have it: The cesarean rate is now 50% higher than it was in 1980. (Hamilton BE, Martin JA, & Ventura SJ. 2011)  The rate of childhood obesity has tripled. (Ogden C. & Carroll M., 2010) Is this just a coincidence?

Theories abound as to the cause of the childhood obesity epidemic. It’s all those sodas and sports drinks laden with high fructose corn syrup. Or it’s sugary, fatty, super-sized fast food. Or video games, the loss of Physical Education at school, bad parenting, unsafe neighborhoods, too little sleep, too much schoolwork, or all of the above. Just about any variable you can think of has been scrutinized for obesogenic potential.

And now, thanks to Dr. Susanna Huh and her research team at Harvard University, we can add cesarean section to the list of suspects.

Creative Commons photo

Huh’s team studied 1,255 mother-child pairs recruited between 1999 and 2002 as part of Project Viva, a longitudinal prebirth cohort of mothers and babies in eastern Massachusetts. A trained research assistant conducted in-person visits with the mothers during pregnancy, and with mothers and babies shortly after delivery, and at 6 months and 3 years after birth. At each visit the children’s length, weight and skin-fold thicknesses were assessed.

Their results: Children born by cesarean section were twice as likely to be obese at 3 years of age than those born vaginally. (Huh, SY, Rifas-Shiman, SI, Zera, CA, Edwards, JWR, Oken, E, Weiss, ST, & Gillman, MW, 2012) This relationship held up even after adjusting for factors like the mother’s weight, ethnicity, age, education, and parity, and the baby’s gender, gestational age, and birth weight.

The Huh study wasn’t designed to look at the reasons for the increased risk of obesity associated with cesarean birth, but the Harvard team suggested several possibilities:

  1. The most likely culprit is the known alteration of the gut microbiota—the sum total of all the micro-organisms found in the healthy human bowel—caused by cesarean birth. The microbiota of vaginally-born babies is populated by bacteria acquired from the birth canal and maternal rectum. In cesarean-born babies, who do not traverse the birth canal, the microbiota is dominated by bacteria from the skin and the hospital environment. In general, cesarean-born babies have an abnormal gut microbiota: too many carbohydrate-loving Firmicutes bacteria and too few obesity-preventing Bacteroidetes species, compared with the microbiota found in vaginally-born babies. This same gut microbiota profile is associated with obesity in adults; the link between the two appears to be low-level bowel inflammation triggered by the abnormal microbiota, which alters how food is absorbed  from the gut and processed within the body.
  2. The second possibility is that cesarean birth is just a stand-in for something else that’s happening at the same time. In discussing their findings, Huh and colleagues speculate about antibiotics routinely given to women during the course of a cesarean. Antibiotics given during pregnancy may temporarily alter the newborn gut microbiota, but research results are mixed as to whether this is a significant, lasting effect.
  3.  It’s possible that all of this has nothing to do with the gut microbiota. There are maternal and placental hormones, and immune and inflammatory factors, surging in a mother’s (and baby’s) bloodstream during labor. These, obviously, are missing to some extent if she never completes labor, and are largely absent if a cesarean is performed before labor starts. The lack of a normal maternal stress response to labor could adversely impact the development of the newborn immune system, theoretically leading to the gut inflammation associated with obesity.
  4.  Differences in mode of feeding may be involved as well. The study’s cesarean babies breast-fed for a significantly shorter time than did the vaginally-born babies. Though the authors don’t comment on this, early weaning is also associated with alterations of the infant gut microbiota.

My best guess: the cesarean-obesity link is likely a big mash-up of all of these, plus other factors no one has yet even dreamed of. Further research by Dr. Huh’s team and many others in the coming months and years will hopefully clarify the picture.

In the meantime, the risk of future obesity is one more factor maternity care providers and their pregnant clients should weigh before deciding on how a baby will be born.

Would you be likely to share this connection between mode of delivery and childhood obesity with  your students when teaching about benefits and risks of cesarean section?  Do you think if more families knew about this connection, they might make different choices surrounding the labor and birth of their baby and avoid interventions likely to increase their risk of a cesarean birth.  Is this information just one more thing that blames mothers for things that are out of their control?  Please share your thoughts in our comment section. -SM

References

Hamilton BE, Martin JA, Ventura SJ. Births: Preliminary data for 2010. National vital statistics reports; vol 60 no 2. Hyattsville, MD: National Center for Health Statistics. 2011.

 Huh, Susanna Y, Rifas-Shiman, Sheryl L, Zera, Chloe A, Edwards, Janet W Rich, Oken, Emily, Weiss, Scott T, & Gillman, Matthew W. (2012). Delivery by caesarean section and risk of obesity in preschool age children: a prospective cohort study. Archives of Disease in Childhood. doi: 10.1136/archdischild-2011-301141

Ogden Cynthia, & Carroll Margaret, U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, Division of Health and Nutrition Examination Surveys (2010). Prevalence of obesity among children and adolescents: United states, trends 1963-1965 through 2007-2008. Retrieved from CDC/National Center for Health Statistics website: http://www.cdc.gov/nchs/data/hestat/obesity_child_07_08/obesity_child_07_08.htm

About Mark Sloan

Mark Sloan has been a pediatrician and a Fellow of the American Academy of Pediatrics for more than 25 years. Dr. Sloan graduated from the University of Notre Dame in 1975, received his medical degree from the University of Illinois, Chicago, in 1979, and completed his pediatric training at the University of Michigan. Since 1982 he has practiced with the Permanente Medical Group in Sacramento and Santa Rosa, California, where he was Chief of Pediatrics from 1997 to 2002. He is an Assistant Clinical Professor in the Department of Community and Family Medicine at the University of California, San Francisco. Dr. Sloan’s first book, Birth Day: A Pediatrician Explores the Science, the History and the Wonder of Childbirth was published in 2009 by Ballantine Books. His writing has appeared in the Chicago Tribune, the San Francisco Chronicle, the San Francisco Examiner, and Notre Dame Magazine, among other publications. Dr. Sloan can be reached through his blog.

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The Homebirth Summit: Providing Much-Needed Multi-Stakeholder Collaboration

November 15th, 2011 by avatar

With the recent Homebirth Summit that took place in Warrenton, VA October 20-22, our country has witnessed increased attention on the state and incidence of this birthing option in the United States.  The Summit organizers have published the outcomes of the event, including Consensus Statements which can be viewed here.  Additionally, you can read comments about the Summit from attendees on various blog sites like Rixa Freeze’s Stand and Deliver, pediatrician Mark Sloan’s blog site (part one and part two) and Childbirth Connection’s Transforming Maternity Care blog site—written by former S&S editor, Amy Romano.

When flipping through the fall issue of the peer-reviewed journal Birth, I landed on the study, United States Home Births Increase 20 percent from 2004 to 2008 (MacDorman, Declerq and Mathews, 2011).  This 20 percent increase isn’t really surprising to me—there is so much momentum in the taking back childbirth renaissance.  The opening paragraph of the article reminds us how much birth location has changed over the past ~ 100 years:

 

Major changes in United States childbearing patterns have occurred over the past century. At the beginning of the last century, almost all United States births took place outside a hospital, the vast majority at home. However, by 1940, only 44 percent of births occurred outside a hospital, and by 1969 this percentage had declined to about 1 percent, where it has remained relatively stable for several decades.”

 

When looking at the Trends by State section of the article, I was interested to find the state in which I live, Montana, boasts the highest homebirth rate (2.18%).  That’s compared to the country’s over-all current homebirth rate of 0.67% in 2008 (most recent data).  While this trend feels significant (especially to homebirth advocates here in the Big Sky state) philosophical dichotomies still exist.

As a part of an email conversation I had with a friend the other day, I was yet again reminded of the age-old  riff between hospital-based and home-based birth providers or, more accurately, the cracks birthing women fall into when attempting to traverse the chasm between these two models of care.

This friend of mine, a doula whose family recently relocated to a very small northeastern Montana town, is pregnant with her second child.  Her first birth was successfully attended by a midwife at a birthing center in the town from which they recently moved.  Desiring the same level of skilled, attentive, compassionate maternity care, my friend began her search for a midwife who would look after her throughout her current pregnancy, labor, delivery and postpartum care.  And yet, due to their rather remote location, she found a lack of midwifery care in her exact locale.  Hoping to piece together her prenatal care from readily available care providers (a local obstetrics clinic) and the philosophical maternity care she truly desires, she hoped to attend regular prenatal care appointments with an OB who was willing to co-supervise the pregnancy with a more distant midwife.  We’re talking true, interdisciplinary collaboration, here.  However, when the OB clinic got wind of this plan, they flat-out refused to work in conjunction with a midwife, or to provide my friend with prenatal care if she chose to also work with a midwife.  So, for now, my friend is tending to her own prenatal care, punctuated with telephone calls and intermittent visits with the midwife she has hired (who lives 270 miles away).

If this story is at all reflective of the state of maternity care collaboration in our country, then the multi-stakeholder conversations that took place at the Homebirth Summit are more important than ever.

 

What are your thoughts on the Homebirth Summit?

 

 

Posted by:  Kimmelin Hull, PA, LCCE, FACCE

 

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