This study was a randomized clinical trial conducted at 2 hospitals in a single university-based medical center in New York City. Women were recruited for the study between October 2017 and February 2018. Eligible patients included those with singleton pregnancies scheduled for cesarean delivery at ≥37 weeks’ gestation. Women were excluded from the study if a delay in umbilical clamping could result in adverse outcomes for the mother or child; if they had preeclampsia, maternal anemia, or bleeding disorders; or if they planned to store umbilical cord blood.
A total of 113 women were enrolled in the study and randomly assigned to the delayed umbilical cord clamping group (n=57) or the immediate umbilical cord clamping group (n=56) in the operating room. Immediate umbilical cord clamping was defined as clamping within 15 seconds of birth; delayed umbilical cord clamping was defined as clamping at 60 seconds after delivery. Hemoglobin levels were assessed on a complete blood count preoperatively (within 72 h before delivery) and on postoperative day 1. The primary outcome was the change in maternal hemoglobin levels from preoperative to postoperative day 1. Secondary outcomes included change in neonatal hemoglobin levels at 24 to 72 hours of life, Apgar scores, surgical duration, estimated blood loss, postpartum hemorrhage, need for blood transfusion, and uterotonic administration.
No significant difference was found in maternal blood loss between the 2 groups. The mean hemoglobin level on the first postoperative day was 10.1 g/dL in the delayed group and 9.8 g/dL in the immediate group [95% confidence interval (CI): 9.8-10.4 and 95% CI: 9.5-10.2, respectively]. For both groups, the hemoglobin levels decreased from preoperative to postoperative day 1, falling −1.90 g/dL in the delayed group and −1.78 g/dL in the immediate group (95% CI: −2.14 to −1.66 and 95% CI: −2.03 to −1.54, respectively). The mean difference was 0.12 g/dL (95% CI: −0.22 to 0.46; P=0.49). With regards to the secondary outcomes, hemoglobin levels at 24 to 72 hours of life were available for 90 of the 113 neonates (79.6%). The hemoglobin level was significantly higher in those who received delayed umbilical cord clamping [18.1 g/dL (95% CI: 17.4-18.8)] versus those who received immediate clamping [16.4 g/dL (95% CI: 15.9-17.0)]. The mean difference was 1.67 g/dL (95% CI: 0.75-2.59; P<0.001). There were no statistically significant differences in secondary maternal outcomes.
In conclusion, for women who had a planned cesarean delivery, delayed umbilical cord clamping showed no significant difference in maternal hemoglobin levels on the first postoperative day compared with those who underwent immediate umbilical cord clamping.
In 2017, the American College of Obstetricians and Gynecologists recommended that the clamping of the umbilical cord be delayed 30 to 60 seconds after birth in term and preterm neonates who do not require neonatal resuscitation. This delay increases the transfer of blood to the neonate, increasing neonatal hemoglobin. This increase in hemoglobin has many beneficial effects for the neonate. There is an ∼20% increase in blood volume. The increase in blood volume and iron stores persists for the first several months which has been shown to improve motor skills and social function later in life. For the preterm infant, there is a lower risk of intraventricular hemorrhage and necrotizing enterocolitis.1 For those infants who require resuscitation, delayed cord clamping is not recommended; this study supports this stance as those infants with delayed cord clamping had a lower umbilical cord pH. While statistically significant, the lower value was not clinically significant for a healthy neonate. For a neonate who already has an acidosis and requires resuscitation, the delay should be avoided to prevent further worsening of the acidosis.
A question that the study did not address is the appropriate time period to administer oxytocin when there is a delay in umbilical cord clamping. There has been a trend towards the administration of a small bolus of oxytocin (3 IU) at the time of delivery.2 This bolus is generally all that is required. In the current study, there was no comment on when the oxytocin was administered. With a delay in cord clamping, there are 3 time periods in which the oxytocin may be administered: at delivery, at cord clamping, and at the time of delivery of the placenta. Since decreasing blood loss after delivery requires adequate uterine tone, the timing of the administration of oxytocin is critical. In the study examining the bolus of oxytocin, 3 IU were administered at the time of delivery of the fetus, not cord clamping.2 Uterine tone was adequate as compared with starting an infusion of oxytocin. This study was performed before the practice of delayed clamping of the umbilical cord.
The current evidence regarding management at cesarean delivery is that the umbilical cord should not be clamped until 30 to 60 seconds after delivery of the neonate to allow for the continued transfusion of blood into the neonate. This practice is only done if resuscitation of the neonate is not required as delaying the clamping of the umbilical cord will result in a statistically significant and clinically insignificant decrease in umbilical cord pH. This decrease is clinically insignificant in healthy neonates but may not apply to the acidotic neonate. Oxytocin is administered in the delivery period to increase uterine tone and decrease blood loss. It is unclear when the oxytocin should be administered in the setting of delayed cord clamping. It may be helpful for the authors to send an addendum describing their management of oxytocin so that similar results may be obtained in other institutions.
Comment by Robert Gaiser, MD
1. American College of Obstetricians and Gynecologists. Delayed umbilical cord clamping after birth. Committee Opinion 684; 2017.
2. Kovacheva VP, Soens MA, Tsen LC. A randomized, double-blinded trial of a “Rule of Threes” algorithm versus continuous infusion of oxytocin during elective cesarean delivery. Anesthesiology. 2015;123:92–100.