There are times in our medical careers where we see a shift in thought that leads to a completely different way of doing things. This happened with episiotomy in the last few decades. Most recently trained physicians cannot imagine doing routine episiotomy with every delivery, yet it was not so long ago that this was common practice.
Episiotomy was supported in Medline indexed publications as early as the 1920s(1), and many publications followed in support of this procedure. But by as early as the 1940s, publications began to appear that argued that episiotomy was not such a good thing(2). Over the years the mix of publications changed, now the vast majority of recent publications on episiotomy focus on the problems with the procedure, and lament why older physicians are still doing them (3) (4). And over all this time, practice began to change.
It took a long time for this change to occur, and a lot of data had to accumulate and be absorbed by young inquisitive minds before we got to where we are today, with the majority of recently trained OBs and midwives now reserving episiotomy only for rare indicated situations.
Though this change in episiotomy seems behind us, there are many changes that are ahead of us. One of these changes, I believe, is in the way obstetricians handle the timing of cord clamping.
For the majority of my career, I routinely clamped and cut the umbilical cord as soon as it was reasonable. Occasionally a patient would want me to wait to clamp and cut for some arbitrary amount of time, and I would wait, but in my mind this was just humoring the patient and keeping good relations. After all, I had seen all my attendings and upper level residents clamp and cut right away, so it must be the right thing, right?
Later in my career I was exposed to enough other-thinking minds to consider that maybe this practice was not right. And after some research I found that there was some pretty compelling evidence that indeed, early clamping is harmful for the baby. So much evidence in fact, that I am a bit surprised that as a community, OBs in the US have not developed a culture of delayed routine cord clamping for neonatal benefit.
I think that this is a part of our culture that should change. This evidence is compelling enough that I feel like a real effort should be made in this regard. So to do my part in this, I am blogging about it.
As this is Academic OB/GYN, of course I am going to lay out this evidence I speak of. But before I do that, I want to present some logical ideas under which this evidence ought to be considered.
Prior to the advent of medical delivery, and for all time in animals, it has been the natural way of things for a baby to stay on the umbilical cord for a significant period of time after delivery. Depending on culture and situation, the delay in cord separation could be a few minutes or even a few hours. In some cultures the placenta is left on for days, which of course I find excessive and gross (5). But whatever the culture and time on cord, the absence of immediate cord clamping allows fetal blood that was previously in the placenta to transfuse back into the baby. Studies have demonstrated that a delay of as little as thirty seconds between delivery and cord clamping can result in 20-40 ml*kg-1 of blood entering the fetus from the placenta (6).
Considering this data, I have to think about evolution and function. I am a strong believer in evolution, but even under creationist thinking I have to believe that if the system meant for babies to have been phlebotomized of 50-100 cc of blood at birth, we would have been born with higher hemoglobins. Clearly the natural way of things is for this not to happen.
So does this mean that early cord clamping is necessarily harmful? Absolutely not. But what it means is that the burden of proof is on us to prove that early cord clamping, which amounts to planned fetal phlebotomy, is a beneficial thing. Otherwise, all things being equal we ought to give the tykes a few minutes to soak up what blood they can from the placenta before we cut’em off.
So the question is whether or not there is strong data either way.
It is easy to imagine a randomized study of immediate vs. delayed cord clamping, with quantitative analysis of fetal lab values and clinical outcomes. So easy in fact, that it has been done many times – and in just about every study, there is a clear benefit to delaying cord clamping, even if it is just for 30 seconds after delivery. These benefits include important outcomes such as decreased rates of intraventricular hemorrhage and necrotizing enterocolitis in preterm neonates. Furthermore, aside from some intermittent reports of clinically insignificant polycythemia and hyperbilirubinemia in term infants, there appears to be no harm that can be linked to delayed cord clamping. It feels like being a doctor 10-15 years ago looking to see if there is any data about episiotomy, and finding that there’s a lot, and it says we’ve been doing it wrong for awhile now.
So here’s the data:
Delayed cord clamping in very preterm infants reduces the incidence of intraventricular hemorrhage and late-onset sepsis: a randomized, controlled trial(7)
Randomized 72 VLBW infants (< 1500 grams) to immediate or delayed cord clamping (5-10 vs. 30-45 seconds). Delayed cord clamp infants had significantly less IVH (5/36 in delayed group vs. 13/36 in immediate group, p = 0.03) and less late onset sepsis (1/36 vs. 8/36, p = 0.03).
The Inﬂuence of the Timing of Cord Clamping on Postnatal Cerebral Oxygenation in Preterm Neonates: A Randomized, Controlled Trial (8)
Randomized 39 preterm infants to immediate clamping vs. 60-90 second delay, and examined fetal brain blood flow and tissue oxygenation. Results showed similar blood flow between groups, but increased tissue oxygenation in the delayed group and 4 and 24 hours after birth.
Effect of timing of umbilical cord clamping on iron status in Mexican infants: a randomized controlled trial(9)
Randomized 476 infants to immediate or 2 minute delayed clamping and followed them for 6 months. Delayed clamped babies had higher MCVs (81 vs. 79.5), higher ferritins (50.7 vs. 34.4), and higher total body iron. Effects were greater in infants born to iron deficient mothers. Delayed clamping increased total iron stores by 27-47mg. A follow up study showed that lead exposed infants with delayed clamping also had lower serum lead levels than immediate clamped infants, likely due to iron mediates changes in lead absorption.
A randomized clinical trial comparing immediate versus delayed clamping of the umbilical cord in preterm infants: short-term clinical and laboratory endpoints(10)
Infants delivering at 30 to 36 weeks gestation randomized to immediate vs. 1 minute delay. Delayed group had higher RBC volumes (p = 0.04) and hematocrits (p < 0.005), though there was no difference in RBC transfusions. There was a small increase in babies requiring phototherapy in the delayed group (p = 0.03) but no difference in bilirubin levels between groups.
Immediate versus delayed umbilical cord clamping in premature neonates born < 35 weeks: a prospective, randomized, controlled study (11)
Randomized 60 infants to clamping at 5-10 seconds vs. 30-45 seconds. Delayed clamping infants had higher BPs and hematocrits. Infants < 1500 grams with delayed clamping needed less mechanical ventilation and surfactant. Trend towards more polycythemia in delayed group, but not statistically significant.
And that’s just some of it. I’ll be happy to send you an Endnote file with a pile more of you’d like it. If the burden of proof is on us to prove that immediate clamping is good, that burden is clearly not met. And furthermore, there is strong evidence that delaying clamping as little as 30 seconds has measurable benefits for the infant, especially in premature babies and babies born to iron deficient mothers.
So basically, we should be doing this. I’m going to try to effect some change in my department, but there are a lot of things that need to happen for us to change as a general culture. It can’t just be the OBs. L and D nurses and pediatricians need to buy in as well.
Some people will argue that premature babies need to be brought to the warmer right away for resucitation. I don’t know the answer to this, but it’s worth study. One might think that it is important to intubate a very premature baby right away, but I have to wonder if that intact cord will be better at delivering oxygen to the baby for 30-60 seconds than the premature lungs. Particularly in cases of fetal respiratory acidosis, there is strong logical argument that a baby might be better resuscitated by unwrapping the cord and letting it flow a bit than trying to oxygenate it through its lungs. Until that placenta is detached, you have a natural ECMO system. Why not use it? Certainly there are exceptions to this logical argument, abruption being the biggest one, and perhaps even severe pre-eclampsia and other poor feto-maternal circulation states.
I wonder at times why delayed cord clamping has not become the standard already; why by and large we have not heeded the literature. It is sad to say that I believe it is because the champions of this practice have not been doctors, but midwives, and sometimes we are influenced by prejudice. Clearly, midwives and doctors tend to have some different ideas about how labor should be managed, but in the end data is data. We championed evidence based medicine, but tend to ignore evidence when it comes from the wrong source, which is unfair. It is fair to critique the research and the methods used to write it, but it shouldn’t matter who the author is. In this case, Mercer and other midwives have done the world a favor by scientifically addressing this issue, and their data deserves serious consideration.
To quote Levy et al (12) “Although a tailored approach is required in the case of cord clamping, the balance of available data suggests that delayed cord clamping should be the method of choice.” We ought to heed this advice better. Like episiotomy, this change in practice may take awhile, but we should get it started. I’m going to work on it myself. How about you?
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