Twin Births: Vaginal Delivery Safer Than Caesarean

Norra MacReady

May 09, 2017

Vaginal delivery of twins is associated with less neonatal morbidity and mortality than cesarean delivery, and should be the birth method of choice when the first twin has a cephalic presentation, the authors of a large, population-based study report.

The findings "call for planned vaginal rather than cesarean delivery between 32 and 37 weeks of gestation and strongly support recent American College of Obstetricians and Gynecologists recommendations," Thomas Schmitz, MD, PhD, from the Gynecologic and Obstetric Service at the Hôpital Robert Debré, Paris, France, and colleagues write in an article published in the June issue of Obstetrics & Gynecology.

This shows that "a lower rate of [caesarean] delivery in women carrying twins is not only achievable, but that it is also safer for their neonates," Dwight J. Rouse, MD, adds in an accompanying editorial.

At this time, 75% of twins in the United States are born through cesarean delivery, Dr Rouse, associate editor (obstetrics) of Obstetrics & Gynecology, writes. Reducing that even to 50% would help nearly 17,000 women each year avoid surgery that is both unnecessary and potentially harmful to their newborns.

The additional risk associated with cesarean delivery was seen only when the infants had a gestational age less than 35 or 37 weeks, depending on the risk level of the pregnancy.

The data come from the Jumeaux Mode d'Accouchement (JUMODA) study, a national, observational, prospective, population-based cohort study conducted in France from February 10, 2014, through March 1, 2015. All maternity units that handled more than 1500 pregnancies annually were invited to participate.

The analysis included women who gave birth to twins at or after 32 weeks' gestation, with the first twin in a cephalic position. They were enrolled by their obstetricians immediately after delivery and categorized according to planned mode of delivery: cesarean or vaginal.

The study included 5915 women who delivered twins in 176 maternity units across France. Of those patients, 1454 (24.6%) planned cesarean deliveries, and 4461 (75.4%) planned vaginal deliveries. Ultimately, 61% of the women in the entire cohort delivered both twins vaginally, including 25 women (1.7%) in the planned cesarean group.

Women who planned a cesarean delivery had a mean age of 32.8 ± 5.8 years compared with a mean of 31.4 ± 5.1 years among women who planned a vaginal delivery. Women planning a cesarean delivery also were heavier than women in the planned vaginal delivery group, and also were more likely to have had previous cesarean deliveries and complicated pregnancies and to deliver smaller neonates at an earlier gestational age.

The primary study outcome was a composite of intrapartum mortality, neonatal mortality during the first 28 days of life, and neonatal morbidity, defined as the presence of one or more characteristics such as 5-minute Apgar score less than 4, birth trauma, or respiratory or neurological complications. Overall, this outcome was seen in 5.2% of infants born to mothers in the planned cesarean group and 2.2% of infants in the planned vaginal delivery group (odds ratio [OR], 2.38; 95% confidence interval [CI], 1.86 - 3.05).

To control for potential bias introduced by the differences in risk between women planning cesarean or vaginal delivery, the authors conducted a propensity-matched analysis comparing a subgroup of 2288 women (1144 in each delivery category). The composite neonatal morbidity and mortality rate among infants in the planned cesarean group was 5.3% compared with 3.0% among infants in the planned vaginal delivery group (OR, 1.85; 95% CI, 1.29 - 2.67).

The most common cause of neonatal death in both groups was multiple malformation or genetic syndromes.

In another subgroup analysis that excluded high-risk pregnancies, 564 (14.2%) of the women had planned cesarean deliveries and 3410 (85.8%) had planned vaginal deliveries. "Analyses by gestational age in this subgroup showed that planned cesarean delivery was associated with higher composite neonatal mortality and morbidity only between 32 0/7 and 34 6/7 weeks of gestation," the authors write.

"The propensity-matched and secondary analyses in the low-risk population demonstrated no significant association between planned cesarean delivery and the composite primary outcome."

Two main conclusions can be drawn from these findings, the authors say. "First, high vaginal delivery rates with low neonatal mortality and morbidity are possible for twin pregnancies with a cephalic first twin at or after 32 weeks of gestation nationwide."

Second, planned cesarean delivery was associated with higher neonatal morbidity and mortality, but only among twins born at less than 37 weeks' gestation in the overall cohort, and at less than 35 weeks in the low-risk cohort. "Cesarean delivery before labor is strongly associated with respiratory distress in term and late preterm neonates."

The findings of this study are similar to those obtained in the Twin Birth Study conducted in Canada, Dr Rouse adds. Both trials have shown that, when the first twin has a cephalic presentation, and the appropriate equipment and personnel are available, "at least from 32 weeks of gestation onward, an attempt at vaginal delivery should be the default plan, regardless of the presentation of the second twin."

One study author reports having been a consultant for Procter & Gamble France, and another reports having been a consultant and lecturer for Ferring Laboratories. The other authors and Dr Rouse have disclosed no relevant financial relationships.

Obstet Gynecol. 2017;129:974-975, 986-995.

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