The optimal time for cord clamping in the third stage of labor (early vs delayed) is a subject of continuing debate. Several systematic reviews have shown that delayed cord clamping (DCC) increases placental transfusion, leading to a substantial increase in neonatal blood volume at birth (∼30%). In healthy term infants, the resulting increase in iron stores reduces the risk of anemia. However, it may increase the risk of hyperbilirubinemia, with resulting jaundice requiring phototherapy. Benefits of DCC are also observed in preterm infants. In a recent study, DCC and milking of the umbilical cord in the preterm infant decreased the need for blood transfusions for anemia, the number of transfusions, and the risks of intraventricular hemorrhage, late-onset sepsis, and necrotizing enterocolitis. The use of DCC in preterm infants is more controversial than in term infants because of concern that it may interfere with resuscitation.
The aim of this review was to evaluate relevant data in the medical literature with regard to the optimal timing for umbilical cord clamping. Evidence was obtained on use of DCC and maternal and neonatal outcomes in both term and preterm infants. A search of the following databases was conducted: PubMed Clinical Queries, Trip Database, Cochrane Systematic Reviews, and UpToDate, as well as published guidelines from obstetric and gynecologic societies in Canada, the United States, and the United Kingdom. The preferential source for data was systematic reviews and randomized controlled trials.
The available evidence suggests that DCC may achieve better neonatal outcomes in both term and preterm infants, even in high-income countries where neonatal iron deficiency anemia is rare. The benefits of DCC in term infants seem to outweigh the risks of adverse outcomes, including neonatal jaundice requiring phototherapy. Similarly, evidence in preterm infants demonstrates that DCC or even milking the cord in these babies is beneficial and suggests that they should be considered whenever possible. However, evidence is insufficient to recommend DCC for nonvigorous infants requiring resuscitation.
Faculty of Medicine and Department of Obstetrics and Gynecology, Jewish General Hospital, McGill University, Montreal Quebec, Canada.