Optimal timing of umbilical cord clamping for term and preterm babies.

Deferring cord clamping allows blood flow between baby and placenta to continue for a few moments. This often leads to increased neonatal blood volume at birth. It also allows for longer transition to the neonatal circulation. Optimal timing for clamping the cord remains uncertain. This paper discusses the physiology of placental transfusion and presents the evidence from systematic reviews of randomised trials comparing alternative strategies for cord clamping for both term and preterm births.