LAS VEGAS – according to a recent study.
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The change in maternal hemoglobin from preoperative level to postoperative day 1, the study’s primary outcome measure, was not significantly different whether the umbilical cord was clamped within 15 seconds of delivery or clamping was delayed for 1 minute.
For the 56 women who received immediate cord clamping, hemoglobin dropped a mean 1.78 g/dL; for the 57 women who received delayed cord clamping, the drop was 1.85 g/dL (P = .69). Mean estimated blood loss for the delayed clamping group was numerically higher at 884 mL, compared with 830 mL for the immediate clamping group, but this was not a statistically significant difference (P = .13)
However, the practice did result in significantly greater neonatal hemoglobin measured at 24-72 hours post delivery. Hemoglobin data were available for 90 infants, or about 80% of participants. For the 44 infants in the immediate clamping group, mean hemoglobin was 16.4 g/dL; for the delayed clamping group, the figure was 18.1 g/dL (P less than .01).
Although delayed cord clamping has clear benefits to the neonate, whether the practice adversely affects women undergoing cesarean was not clear, said Stephanie Purisch, MD, who discussed the findings of the two-site, randomized, clinical trial during a fellows research session at the meeting sponsored by the Society for Maternal-Fetal Medicine.
“Maternal outcomes have not been a focus of research” in the cord clamping literature, said Dr. Purisch, from Columbia University, New York. A 2013 Cochrane review found that delayed cord clamping did not change postpartum hemoglobin levels or increase blood loss or the need for transfusion. However, she said, the review included only healthy women who expected a vaginal delivery, so cesarean deliveries were undersampled in the data.
Of the 3,911 deliveries included in all prior randomized, controlled trials of delayed cord clamping, just 87, or 2.2%, were cesarean deliveries, she said. In cesarean deliveries, mean blood loss is double that of vaginal deliveries. Delayed clamping could further increase bleeding because the hysterotomy closure is delayed, said Dr. Purisch, so the question of safety in cesarean deliveries is clinically important.
Faced with this knowledge gap, Dr. Purisch and her colleagues constructed a prospective, randomized, controlled trial of delayed cord clamping in cesarean delivery at term, with the hypothesis that maternal blood loss would be increased by the practice.
Patients were eligible if they had singleton gestations with cesarean deliveries scheduled at 37 weeks’ gestation or more. Patients with known placentation problems, significant maternal or known fetal anemia, maternal bleeding disorders, and preeclampsia were excluded. The study also did not include pregnancies with known fetal anomalies or intrauterine growth retardation, or those in which cord blood banking was planned or the mother would refuse blood products.
In an intention-to-treat analysis, Dr. Purisch and her colleagues randomly assigned participants 1:1 to immediate cord clamping, defined as clamping the cord by 15 seconds after delivery, or delayed cord clamping, in which the umbilical cord was clamped 1 minute after delivery.
Oxytocin was routinely administered to each group on delivery, and there was no umbilical cord milking in either group. For the delayed-clamping group, the infant was kept at the level of the placenta and tended by the pediatric team during the minute before clamping. Dr. Purisch explained that cord clamping was performed before 60 seconds in the intervention group if needed for neonatal resuscitation.
Participants were similar in the two study arms, with a median gestational age of 39.1 weeks at delivery. Most women (60%-64%) had one prior cesarean delivery, with about a quarter having two or more prior cesarean deliveries. Preoperative maternal hemoglobin was 11.6-12.0 g/dL. About 41% of participants were Hispanic, and the median prepregnancy body mass index for participants was about 27 kg/m2.
Looking at secondary outcome measures, there was no difference in rates of postpartum hemorrhage or uterotonic administration between the two groups (P = .99 for both). Hemoglobin levels at postoperative day 1 were numerically higher for the delayed cord clamping group, but the difference wasn’t significant (10.2 vs. 9.8 g/dL; P = .18). Just two women, both in the immediate cord clamping group, required blood transfusions.
Additional neonatal secondary outcome measures included birth weight, Apgar scores at 1 and 5 minutes, the need for phototherapy for jaundice, and umbilical cord artery pH. There were no between-group differences except that umbilical cord artery pH was slightly lower in the delayed group (7.2 vs. 7.3; P = .04).
“Delayed cord clamping is not associated with increased maternal blood loss … but it does achieve higher neonatal hemoglobin levels at 24-72 hours of life,” said Dr. Purisch. “These results provide support for the application of current [American College of Obstetricians and Gynecologists] recommendations to women planned for cesarean delivery.”
The study was funded by the Columbia Maternal-Fetal Medicine Fellow Research Fund. Dr. Purisch reported no conflicts of interest.
SOURCE: Purisch, S. et al. Am J Obstet Gynecol. 2019 Jan;220(1):S37-38, Abstract 47.