When Should We Clamp the Umbilical Cord?

Abstract

After completing this article, readers should be able to: 1. List factors that may influence redistribution of blood between placenta and newborn. 2. Describe three methods of determining whether a placental transfusion takes place. 3. Characterize the physiologic effects of placental transfusion on the neonate. 4. Describe the possible effects of early and delayed cord clamping on infants and mothers. “Another thing very injurious to the child is the tying and cutting of the navel string too soon, which should always be left till the child has not only repeatedly breathed but till all pulsation in the cord ceases. As otherwise the child is much weaker than it ought to be, a part of the blood being left in the placenta which ought to have been in the child and at the same time the placenta does not so naturally collapse and withdraw itself from the sides of the uterus, and is not therefore removed with so much safety and certainty.” —Erasmus Darwin (1801) (1) The question of when, after delivery, the umbilical cord should be clamped has been debated for many years. The question was posed well over a century ago (and as can be seen from the above quotation, probably more than two centuries ago), but despite considerable investigation, a definitive answer remains somewhat elusive. The debate revolves around what constitutes “early” versus “late” clamping of the cord and what is the most optimal time for clamping to benefit the infant. In recent years, the focus has shifted from the prevention of respiratory distress syndrome (RDS) (in the postsurfactant era) to minimizing the need for subsequent blood transfusions with delayed cord clamping in preterm infants. This review covers the factors involved in placental transfusion and summarizes short- and long-term effects of such transfusion on the term and preterm infant. More correctly, …