The Amount of Fetal Blood Remaining in the Placenta at Birth ∗

Summary

The amount of fetal blood remaining in placenta and cord has been determined in 84 births, making use of the total amount of fetal hemoglobin in relation to its concentration in cord blood of the same infant. Expressed as percentage of body weight, the amount is 4.5 in 62 vaginal deliveries with prompt clamping of the cord, 2.5 in 5 cases of placental transfusion, and 5.1 in 16 cesarean sections. In 4 cases of preeclampsia the amount is markedly greater than in other comparable births. The possibility is suggested that events shortly before birth, perhaps during the second stage of labor, influence the partition of blood between fetus and placenta.