Delayed Versus Immediate Cord Clamping and Changes in Neonatal Hemoglobin

The purpose of this study is to determine whether the timing of the clamping of the umbilical cord after delivery has an impact on neonatal hemoglobin and hematocrit, tests that determine the number of red cells in the blood and their ability to carry oxygen. The study hypothesis is that delaying cord clamping until cord pulsation has ceased will increase the neonatal blood volume and thereby increase the hemoglobin and hematocrit.

As the communication between the placenta and fetus, the umbilical cord provides oxygen and nutrients until the time of delivery. Even after delivery, placental respiration continues for a short time and the newborn infant continues to receive blood from the placenta until physiologic closure of the cord vessels terminates the transfusion. While most term infants can tolerate variations in blood volume, those who are compromised by prematurity, cesarean delivery or cord compression in utero may require blood transfusions if the cord is clamped before pulmonary perfusion is established. Delayed cord clamping is believed to provide a greater supply of blood to perfuse the lungs without robbing blood from the other organs.

In uncomplicated vaginal deliveries the umbilical cord traditionally has been clamped immediately after delivery, more for the doctor's convenience than for any consideration regarding the health of the infant. Both immediate and delayed cord clamping are accepted as routine standard of care at delivery, depending on the circumstances. However, some clinicians and researchers have suggested that by delaying the clamping of the umbilical cord, the placental transfusion to the newborn is maintained, optimizing blood volume and hemostasis.

Several European research studies have suggested that delayed cord clamping increases newborn hemoglobin and hematocrit. However, these studies were not performed under properly controlled conditions and thus have failed to gain general acceptance.

We propose to recruit 150 women who present for vaginal delivery at Tulsa Regional Medical Center. We believe this number of volunteers is possible to enroll in the allotted five months for data collection. A power analysis for this sample size was performed by Dr. Mark Payton, professor of statistics at the OSU Stillwater campus. He estimated that a difference of 0.3 standard deviations has a power of just over 95%.