NICHD scientist explains what’s known about when to cut, and when to wait
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Barrett Whitener: How soon after a baby is born should the practitioner wait to cut the umbilical cord? That simple question has no easy answer. Cutting the cord too soon after birth might stress the baby’s heart, increase the risk for bleeding inside the brain, and increase the risk for anemia and iron deficiency. Waiting too long may result in the infant having too many red blood cells. The excess red cells could lead to newborn jaundice, a kind of blood poisoning resulting from the breakdown of the extra red cells.
From the National Institutes of Health, I’m Barrett Whitener, and this is “Research Developments,” a podcast from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the NICHD.
Recently, Australian scientist Stuart Hooper reviewed the major studies on the science of when to clamp the umbilical cord after birth. Much of this extensive body of research was funded by the NICHD. To help us understand these findings, we have invited Dr. Tonse Raju, Chief of NICHD’s Pregnancy and Perinatology Branch.
Before we get started, let’s stop to consider for a minute the incredible transition an infant’s heart and lungs must make shortly after birth. In the womb, the lungs cannot take in air, so the baby doesn’t inhale and exhale. The lungs are filled with fluid. Adults get oxygen from the lungs, but the fetus gets its oxygen from the umbilical cord. The two chambers of the infant heart beat at roughly the same interval, to bring oxygen from the umbilical region to the tissues and send it back again. At birth, this arrangement changes rapidly. The blood flow switches, so that now it fills the lungs.
Now, here’s the reason for concern: If you cut the cord before the infant clears its lungs, takes that first breath, and transitions its blood circulation to the lungs, you could deprive it of blood and oxygen—and also stress the heart.
I’m very happy you could be with us today, Dr. Raju.
Tonse Raju: Thank you.
Mr. Whitener: First, we do have recommendations for when to cut the cord in infants born preterm, don’t we?
Dr. Raju: Yes. The American College of Obstetricians and Gynecologists have recommended that at least 30 seconds of waiting in preterm babies would be beneficial for the preterm baby’s cardiovascular system.
Mr. Whitener: Before cutting the cord, so that—
Dr. Raju: Before you cut the cord, yes, a minimum of 30 seconds.
Mr. Whitener So that they can be sure to get the sufficient amount of oxygen to the brain.
Dr. Raju: That’s correct, so they can get a sufficient amount of oxygen—blood to go into the lungs, and then oxygenated blood can go to the brain.
Mr. Whitener: Now, what about full-term infants? Can we say with certainty when the cord should be clamped for them?
Dr. Raju: Well, the World Health Organization has recommended that even in full-term babies, waiting up to 2 minutes after birth would be ideal because that would enhance the amount of blood they get, and most importantly, they end up getting more iron and more red cells and more iron. This will prevent them from having potentially iron deficiency anemia, which is a major problem in the rest of the world, particularly because iron is important for learning and growth, and deficiency of iron can make you susceptible for infections. And worldwide, almost a third to one-half of children in their first year are significantly deficient in iron. So World Health has made a strong recommendation that you need to wait until at least 2 minutes or longer before you cut the cord at birth.
Mr. Whitener: And in the United States, is it true that physicians have more leeway as to when to cut the umbilical cord?
Dr. Raju: Yes. For term babies in the United States, we don’t have a specific recommendation, mainly because, on the one hand, maybe the incidence of iron deficiency anemia is not that high, because in our food materials—in bread and other things that we eat—there is iron fortification. So we are unlikely to suffer as many babies or people with iron deficiency anemia.
Also, there is a small chance these babies, if they get more blood, then they can end up getting jaundice. That is why the ACOG decided not to make any specific recommendation for term babies in the United States.
Mr. Whitener: Now, we mentioned the jaundice a moment ago. Are there other potential risks for cutting the umbilical cord—waiting too long?
Dr. Raju: Well, as for us, we know now there are no potential risks. There are more than close to 10,000 babies have been studied worldwide, and there are what we call “meta-analysis” or systematic reviews that combine these results, and from that we have learned that there’s really no obvious negative effect. Even the question of jaundice is probably much smaller than some people are afraid of, because, you know, we need to be worried about jaundice in every baby, not just the babies who get either earlier or delayed cord clamping. All babies could become—almost 80 percent of babies get jaundice in the first week of life— and we need to make sure that a small number of these babies don’t end up having too much jaundice. So we need a planned follow-up; and if you don’t do that, there’s a problem, irrespective of the time of cutting the cord.
Having said that, the other issues concerning the potential dangers of cord clamping, people have been worrying that: is there a problem for the mother, for instance? Can she end up having more bleeding after what we call “postpartum hemorrhage”? All these studies have now shown that there is no—there are no side effects at all for mother’s health and mother’s outcome, and almost all other outcomes in the babies have been equivocal, same as babies with whom you cut the cord right away. So a lot of people actually are saying that delayed cord clamping is actually the standard, and early cord clamping has no evidence, and we have been doing something without any good evidence why you had to cut the cord immediately after the baby is born.
Mr. Whitener: So do you feel that this study may have implications for the way this is done in the U.S.?
Dr. Raju: Absolutely, I think. It is already—I am so pleased to say that a lot of people have been changing their practice, and they are already seeing some positive benefits because they used to be worried about preterm babies, that if I wait long, will I be delayed in starting any resuscitation if the baby needs resuscitation?
But people are learning that waiting for 30 seconds or longer itself is the first step of resuscitation, because that way, the baby is already getting the blood that it needs from the placenta, so that baby’s not in trouble.
Mr. Whitener: Are there circumstances where cutting the umbilical cord right away is an important thing to do?
Dr. Raju: Yes, I would think so. Especially, let’s assume that there has been a significant fetal distress, and baby’s in trouble already. And there may be umbilical cord tied around the neck of the baby several times. Then the obstetrician really wants to get the baby out, cut the cord, and give the baby to the pediatrician, so that the resuscitation can be carried out. That is one situation I would imagine I can think of when immediate clamping of the cord may be required.
And another situation can be when there is a hemorrhage, even before the baby is delivered, and this can occur if there is an abnormal insertion of the placenta. If the placental is already very low insertion, when the uterus is—the cervix is dilating, the placenta can rupture, and the mom can bleed before the baby comes out. And there are situations, what we call “abruption of the placenta”—placenta gets separated out from the uterus wall even before the baby comes out. All these things are emergency conditions, both for the baby and the mother, and in those situations, the obstetricians may elect to clamp the cord right away.
Mr. Whitener: So given these various circumstances that can confront physicians who are delivering babies, when do you think we could expect some information to guide new mothers and practitioners on this issue? Is the NICHD currently funding further research?
Dr. Raju: Right. I mean, first of all, I want to underline that these complications I just listed are rare. They are not everyday occurrence, thankfully—probably about maybe 5 percent of all births may take place. So the incidence is not that common.
Now, having said that, they are important for us to consider, and yes, NICHD is funding many aspects related to cord clamping research. So one of the other—another way of enhancing blood flow to the baby is after the baby is born. We call it “cord milking”: That means an obstetrician can provide a longer segment of the umbilical cord, and the pediatrician can untwist the umbilical cord and milk it a couple of times, so the blood that is remaining in the umbilical cord will go to the baby. And studies coming from Japan have shown that milking is as effective as delayed cord clamping, and we are really—we are funding a study to see is that true, not only immediately, but also in the long-term outcome of preterm babies, so that study is ongoing now.
Mr. Whitener: Well, thanks very much for talking with us today.
Dr. Raju: Thank you.
Mr. Whitener: I’ve been speaking with Dr. Tonse Raju of the NICHD.
About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): The NICHD sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. For more information, visit the Institute's website at http://www.nichd.nih.gov/.