DALLAS (FRONTLINE MEDICAL NEWS) – Timing of maternal oxytocin administration did not affect total placental transfusion volume accomplished via delayed umbilical cord clamping, according to a recent randomized, controlled trial.

Of 144 infants born to women who consented to randomization, those whose mothers received intravenous oxytocin within 15 seconds of delivery (n = 70) gained a mean 86 g (standard deviation, 48; 95% confidence interval, 74-97) in the 3 minutes after delivery, before umbilical cord clamping. Infants whose mothers received oxytocin when the umbilical cord was clamped 3 minutes after delivery (n = 74) gained 87 g (SD, 50; 95% CI, 75-98; P for difference between groups = .92). The findings were presented during an abstract session at the meeting sponsored by the Society for Maternal-Fetal Medicine.

The study helps resolve questions in an area of obstetric practice that affects both mother and infant: Prompt administration of oxytocin after delivery helps reduce the risk of maternal postpartum hemorrhage, while the bolus of placental blood delivered by delayed umbilical cord clamping provides benefit to the infant by increasing hemoglobin and hematocrit and reducing the incidence of iron deficiency during the newborn period.

It had not previously been known whether immediate oxytocin administration enhanced or diminished placental transfusion volume, said Daniela Satragno, MD, the study’s first author.

The investigators had hypothesized that immediate oxytocin administration would increase the volume of placental transfusion, said Dr. Satragno, of Argentina’s Foundation for Maternal and Child Health. However, their study didn’t bear this out. “When umbilical cord clamping is delayed for 3 minutes, infants receive a clinically significant placental transfusion which is not modified by the administration of IV oxytocin immediately after birth,” wrote Dr. Satragno and her coauthors in the abstract accompanying the presentation.

The study in the American Journal of Obstetrics & Gynecology included healthy term infants born via vaginal delivery; Dr. Satragno said that consent was obtained from mothers in early labor, and that study recruiters did not approach women who were in more advanced stages of labor because of ethical concerns. Women with high-risk pregnancies and those with known fetal anomalies were excluded, as were any who required forceps deliveries, neonatal resuscitation, and those whose deliveries involved a short umbilical cord or a nuchal cord.

In order to estimate the volume of placental transfusion, all infants were weighed on a 1-g precision scale placed at the level of the vagina both immediately after birth and after the umbilical cord was clamped at 3 minutes after delivery. All participating mothers received 10 IU of oxytocin, with the timing varying by intervention arm. A figure of 1.05 g/cc of blood was used to calculate transfusion volume, with change in infant weight used as a proxy for transfusion volume.

Hematocrit levels were also similar between the two groups: infants whose mothers received immediate oxytocin had a mean hematocrit of 57% (SD, 5), while those whose mothers had delayed oxytocin administration had a mean hematocrit of 56.8% (SD, 6).

Dr. Satragno and her collaborators also looked at a number of other secondary outcome measures, including incidence of jaundice and polycythemia in the infant, and maternal postpartum hemorrhage. There were no such adverse events that reached the level of clinical relevance among any of the mothers or infants in the study population, she said.

A larger study had been planned, said Dr. Satragno, but the data safety monitoring board recommended stopping the study for futility after the prespecified interim analysis of data from 144 patients – just 25% of the originally planned sample size.

In response to an audience question, Dr. Satragno acknowledged that blinding was not feasible with their study design, but that she did not think that this affected physician management in the first few minutes postpartum. She noted that delayed cord clamping has been an area of active research at her institution, and protocols are well established.

“Based on the available data, a recalculation of the sample size for a difference of 20% in the volume of placental transfusion would result in a trial of an unrealistically large magnitude,” said Dr. Satragno.

The study was funded by the Foundation for Maternal and Child Health. The authors reported no conflicts of interest.

SOURCE: Satragno D et al. Am J Obstet Gynecol. 2018 Jan;218:S26 .