Delayed clamping vs milking of umbilical cord in preterm infants: a randomized controlled trial

It has been established that delayed umbilical cord clamping in preterm infants results in improvement in neonatal anemia, need for transfusion, incidence of necrotizing enterocolitis, and intraventricular hemorrhage by increasing neonatal circulating blood volume. However, the effects of umbilical cord milking as an alternative to delayed clamping in preterm infants are unclear.

The primary objective of this study was to compare the effect of delayed clamping vs milking of the umbilical cord on the initial hematocrit concentration in preterm births (23-34 weeks gestation). In addition, we sought to compare the effects of delayed clamping vs milking on the incidences of intraventricular hemorrhage, necrotizing enterocolitis, and need for transfusion (secondary objectives).

The study was an unblinded randomized controlled trial of singleton preterm infants who were born 23 weeks 0 days to 34 weeks 6 days gestation and were assigned to 1 of 2 controlled study groups: delayed cord clamping for 60 seconds or milking of the cord towards the infant 4 times before clamping. Randomization occurred via block randomization with an allocation ratio of 1 to 1. The patients' third stage of delivery was standardized for route of delivery and randomization arm. All comparisons were preformed with an intent-to-treat analysis approach. The study was powered at 80% with a probability value of .05 for the primary outcome measure of a hematocrit difference of 3% between the 2 groups.

Of the 204 randomized patients, 104 were assigned to the delayed subgroup, and 100 were assigned to the milking subgroup. There were no significant differences in baseline maternal characteristics noted between groups. Though there was not any statistically significant difference in neonatal outcomes between the cord clamping and milking groups, the occurrences of transfusion (15.5% vs 9.1%; P=.24), necrotizing enterocolitis (5.8% vs 3.0%; P=.49), and intraventricular hemorrhage (15.5% vs 10.1%; P=.35) were all lower in the milking group. The milking group had higher initial hematocrit concentration compared with the delayed clamping group, although this was not significant (51.8 [6.2%] vs 49.9 [7.7%]; P=.07]. Peak bilirubin levels and need for phototherapy were similar between groups.

This study demonstrates that milking the umbilical cord may be an acceptable alternative to delayed cord clamping because there were similar effects on neonatal hematocrit concentrations and the need for neonatal transfusions and no increased risk for complications or neonatal morbidity. The present data support the concept that milking of the umbilical cord may offer an efficient and timely method of providing increased blood volume to the infant.