Delayed Cord Clamping in Preterm Neonates

Overview

Delayed cord clamping (DCC) from 30 to 60 seconds allows blood to continue to flow from the placenta through the umbilical cord to the infant, thus resulting in a placental transfusion. This transfusion may improve circulating volume at birth leading to a smoother postnatal transition and overall improved outcome for preterm infants. The average blood volume delivered with DCC up to 90 seconds in preterm infants has been estimated to be about 12 ml per kg with vaginal deliveries resulting in slightly higher transfusions compared to cesarean deliveries. Several several short-term benefits have been described including a reduction in the need for blood transfusions as well as a possible reduction in intraventricular hemorrhage and necrotizing enterocolitis. All mothers with threatened preterm delivery between 28 and 34 6/7 weeks will be approached for the study. Following consent, the infant will be randomly assigned to either a 30 or 60 second delay in cord clamping in the delivery room. If the infant is not breathing by 30 seconds, the cord will be clamped and the infant moved to a resuscitation area. The primary outcome is a 3 percent difference in the hematocrit at one hour (routinely obtained on all babies). With approximately 75 neonates in each group (30 and 60 second DCC), there is 80% power to detect a difference in the mean hematocrit of 3% using a two-sample t-test with a 0.05 two-sided significance level.

Placental transfusion at birth is thought to have immediate, short-term and long-term benefits for the neonate. Delaying cord clamping is thought to allow for a smoother postnatal transition as the necessary cardiopulmonary changes take place specifically when the infant establishes spontaneous respirations and/or experimentally when mechanical ventilation is initiated. By allowing the infant to establish respirations, the pulmonary vascular bed is able to relax prior to the removal of the low-resistance placental vascular bed, thus avoiding a reflexive bradycardia. A 2012 Cochrane review of DCC in preterm infants has suggested several short-term benefits including a reduction in the need for blood transfusions as well as a possible reduction in intraventricular hemorrhage and necrotizing enterocolitis. The American College of Obstetrics and Gynecology (ACOG) published a committee opinion in December of 2012 stating that current evidence supports delayed cord clamping in preterm infants. They go on to support that DCC up to 30-60 seconds has been shown to improve transitional circulation, decreased the need for blood transfusion, and may even reduce the incidence of intraventricular hemorrhage. The primary objective of this study is to determine if delayed cord clamping up to 60 seconds leads to an improved postnatal transition as demonstrated by higher initial hematocrit at 30 minutes in preterm neonates born between 28 and 34+6/7 weeks gestation. The investigators will determine whether there is a significant difference in this primary outcome with delays of 30 seconds versus 60 seconds. A secondary objective will be to determine the effect of DCC on additional measures such as Apgar scores, initial heart rate, initial temperature, blood pressure measures, fluid resuscitation and/or the need for pressors, peak bilirubin, and days on phototherapy. Inclusion Criteria: Preterm infants born between 28 and 34+6/7 weeks gestation. Exclusion Criteria: Infant with suspected placental abruption, bleeding from placenta previa, terminal bradycardia, cord prolapse, meconium, or any major congenital anomalies. All mothers with threatened preterm delivery between 28 and 34 6/7 weeks will be approached for the study. If consent is obtained, the infant will be randomly assigned to either a 30 or 60 second delay of cord clamping in the delivery room. All delivery room staff will be notified of the assignment prior to the delivery. The Neonatal Intensive Care Unit (NICU) staff will be present at each delivery, including a NICU Fellow, a NICU nurse, and/or an neonatal nurse practitioner or pediatric resident. In the case of a C-Section, the NICU fellow will be in sterile gown and gloves in order to assess the infant on the sterile field. The timer will start immediately following delivery of the entire infant. In the case of a vaginal delivery the infant will be placed between the mother's legs or on the mother's abdomen in the case of a cesarean section. The fellow will evaluate the infant to assess onset of respirations while stimulating and covering the infant in a plastic wrap. If the infant has good tone and sustained breathing, the umbilical cord will continue to be unclamped though a maximum of 60 seconds. If the infant has not begun to establish respirations at 30 seconds, the cord will be clamped and the infant will be transferred to the radiant warmer regardless of their original assignment. The primary outcome is a 3 percent difference in the hematocrit at one hour (routinely obtained on all babies). With approximately 75 neonates in each group (30 and 60 second DCC), there is 80% power to detect a difference in the mean hematocrit of 3% using a two-sample t-test with a 0.05 two-sided significance level.