Cesarean section prevents placenta-to-infant transfusion despite delayed cord clamping.

We have adapted and calibrated an accurate method for measuring residual placement blood volume (RPBV). We used this method in 33 normal vaginal deliveries and 18 cesarean section deliveries in which the umbilical cord was clamped from 5 to 118 seconds after delivery. Infants born vaginally received 10 to 20 ml. per kilogram of body weight of placental transfusion when umbilical cord was not clamped until 30 seconds or more after delivery. Equivalent delay of umbilical cord clamping in cesarean section infants produced no placental transfusion.