Timing of Umbilical Cord Clamping in Preterm Infants May Affect Outcomes

The available evidence indicates that a delay in clamping the umbilical cord in preterm infants may be associated with improved neonatal outcomes, according to an intervention review of the effects of early versus delayed umbilical cord clamping.¹

When to clamp the umbilical cord to maximize outcomes in preterm infants currently is unclear. Immediate clamping of the umbilical cord allows for prompt transfer of the infant to the care of a neonatologist. Delayed clamping of the cord-at least 30 seconds-prolongs placental transfusion, which improves circulating blood volume at birth and thus may improve outcomes. The current standard of care during delivery of the placenta involves clamping the cord immediately at birth.

Researchers evaluated 15 studies that met inclusion criteria and involved 738 infants. All births occurred between 24 weeks and 36 weeks of gestation. In the included studies, the maximum delay of cord clamping was 180 seconds. Compared with immediate clamping, a delay in clamping the umbilical cord was associated with fewer infants requiring a transfusion because of anemia, fewer cases of intraventricular hemorrhage, and a reduced risk of necrotizing enterocolitis. Jaundice often is considered a risk of delayed clamping of the umbilical cord, and findings of this review did show that peak bilirubin levels were higher in the delayed clamping group.

For other outcomes, such as infant mortality, grade 3/4 intraventricular hemorrhage, and periventricular leukomalacia, no “clear” differences were found between study groups. However, many of the studies that were included in this analysis had wide confidence intervals and incomplete reporting of data, making it difficult to draw reliable conclusions about how either immediate or delayed clamping affected the primary outcomes for this review.

Although direct comparisons of these results with those of another large study are not possible because of a difference in study participants-preterm infants versus full-term infants of a low-risk pregnancy-it has been shown that there were no differences in the rates of jaundice in infants who were allocated to either immediate or delayed clamping.² However, this result contradicts the findings of this current review as well as another intervention review involving full-term infants: delayed clamping increases the risk of jaundice.^1,3

Pertinent Point:
- Delayed clamping of the umbilical cord for 30 to 120 seconds in preterm infants may be associated with lower transfusion rates, higher rates of circulatory stability, lower rates of intraventricular hemorrhage, and a reduced risk of necrotizing enterocolitis.

References:

1. Rabe H, Diaz-Rossello JL, Duley L, Dowswell T. Effect of timing of umbilical cord clamping and other strategies to influence placental transfusion at preterm birth on maternal and infant outcomes. Cochrane Database Syst Rev. 2012;8. DOI: 10:1002/14651858.CD003248.pub3.
2. 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. BMJ. 2011;343:d7157. doi: 10.1136/bmj.d7157.
3. McDonald SJ, Middleton P. Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes. Cochrane Database Syst Rev. 2008;(2):CD004074.