Author Affiliation: Department of Pediatrics, Women and Infants Hospital, Providence, RI.
Delayed clamping of the umbilical cord at birth results in placental transfusion. The amount of blood transfusion depends on several factors, including timing of cord clamping, initiation of first breath and cry, gravity, mode of delivery, and intensity of uterine contractions at the end of the second stage of labor. It has been estimated that in a vaginally born full-term infant, delaying cord clamping by 2 to 3 minutes results in an increase in neonatal blood volume of approximately 20 to 30 mL per kilogram of body weight.1 Cesarean delivery has the same effect but to a lesser extent.2
Oh W. Timing of Umbilical Cord Clamping at Birth in Full-term Infants. JAMA. 2007;297(11):1257-1258. doi:10.1001/jama.297.11.1257