A step away from immediate umbilical cord clamping
Considering the risks of jaundice and the relative infrequency of iron deficiency in the United States, we should not routinely delay clamping for term infants at this point.
A recent committee opinion developed by the American College of Obstetricians and Gynecologists and endorsed by the American Academy of Pediatrics (No. 543, December 2012) captures this view by concluding that “insufficient evidence exists to support or to refute the benefits from delayed umbilical cord clamping for term infants that are born in settings with rich resources.” Although the ACOG opinion preceded the Cochrane review, the committee, of which I was a member, reviewed much of the same literature.
Timing in preterm infants
Preterm neonates are at increased risk of temperature dysregulation, hypotension, and the need for rapid initial pediatric care and blood transfusion. The increased risk of intraventricular hemorrhage and necrotizing enterocolitis in preterm infants is possibly related to the increased risk of hypotension.
As with term infants, a 2012 Cochrane systematic review offers good insight on our current knowledge. This review of umbilical cord clamping at preterm birth covers 15 studies that included 738 infants delivered between 24 and 36 weeks of gestation. The timing of umbilical cord clamping ranged from 25 seconds to a maximum of 180 seconds (Cochrane Database Syst. Rev. 2012;8:CD003248).
Delayed cord clamping was associated with fewer transfusions for anemia or low blood pressure, less intraventricular hemorrhage of all grades (relative risk 0.59), and a lower risk for necrotizing enterocolitis (relative risk 0.62), compared with immediate clamping.
While there were no clear differences with respect to severe intraventricular hemorrhage (grades 3-4), the nearly 50% reduction in intraventricular hemorrhage overall among deliveries with delayed clamping was significant enough to prompt ACOG to conclude that delayed cord clamping should be considered for preterm infants. This reduction in intraventricular hemorrhage appears to be the single most important benefit, based on current findings.
The data on cord clamping in preterm infants are suggestive of benefit, but are not robust. The studies published thus far have been small, and many of them, as the 2012 Cochrane review points out, involved incomplete reporting and wide confidence intervals. Moreover, just as with the studies on term infants, there has been a lack of long-term follow-up in most of the published trials.
When considering delayed cord clamping in preterm infants, as the ACOG Committee Opinion recommends, I urge focusing on earlier gestational ages. Allowing more placental transfusion at births that occur at or after 36 weeks of gestation may not make much sense because by that point the risk of intraventricular hemorrhage is almost nonexistent.
Our practice and the future
At our institution, births that occur at less than 32 weeks of gestation are eligible for delayed umbilical cord clamping, usually at 30-45 seconds after birth. The main contraindications are placental abruption and multiples.
We do not perform any milking or stripping of the umbilical cord, as the risks are unknown and it is not yet clear whether such practices are equivalent to delayed cord clamping. Compared with delayed cord clamping, which is a natural passive transfusion of placental blood to the infant, milking and stripping are not physiologic.
Additional data from an ongoing large international multicenter study, the Australian Placental Transfusion Study, may resolve some of the current controversy. This study is evaluating the cord clamping in neonates < 30 weeks’ gestation. Another study ongoing in Europe should also provide more information.
These studies – and other trials that are larger and longer than the trials published thus far – are necessary to evaluate long-term outcomes and to establish the ideal timing for umbilical cord clamping. Research is also needed to evaluate the management of the third stage of labor relative to umbilical cord clamping as well as the timing in relation to the initiation of voluntary or assisted ventilation.
Dr. Macones said he had no relevant financial disclosures.
Dr. Macones is the Mitchell and Elaine Yanow Professor and Chair, and director of the division of maternal-fetal medicine and ultrasound in the department of obstetrics and gynecology at Washington University, St. Louis.
