Study shows no benefit with cesarean section for twins

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Twin birth study won’t alter practice

Although the Twin Birth Study was a "massive logistic effort," the findings are unlikely to lead to a major change in the use of cesarean delivery for twin pregnancies, according to Dr. Michael F. Greene.

For one thing, the results do not indicate that all sets of twin should be delivered vaginally, he said.

"Obstetricians exercising their best clinical judgment delivered both twins by cesarean section in nearly 40% of the women assigned to planned vaginal delivery, which undoubtedly contributed to the salutary outcomes," he said, noting that the results nonetheless suggest that "a plan to deliver appropriately selected sets of twins vaginally is a reasonably safe choice in skilled hands."

Still, are the results likely to "bend the cesarean delivery curve for twin pregnancies?" he asked.

"Given the trends in patient demographic characteristics and preferences, the virtual disappearance of vaginal delivery in cases of breech presentation, and the dramatic reduction in instrumented vaginal delivery (and the associated gradual disappearance of the skills necessary to perform these procedures among obstetricians), it seems unlikely that we will see a major change in use of cesarean delivery for twins nationwide," he said.

Dr. Greene is an ob.gyn. at Massachusetts General Hospital, Boston, and an associate editor for the New England Journal of Medicine. He reported having no other disclosures. Dr. Greene’s remarks were in an editorial in response to Dr. Barrett and his colleagues’ study (N. Engl. J. Med. 2013;369:1365-6).



No significant differences were seen in the risk of adverse neonatal outcomes between women with twin pregnancy who underwent planned cesarean delivery and those who underwent planned vaginal delivery as part of the randomized Twin Birth Study.

The rate of a composite outcome of fetal or neonatal death or serious neonatal morbidity among 1,393 women in 25 countries assigned to undergo planned cesarean delivery was 2.2%, compared with 1.9% among 1,393 women assigned to planned vaginal delivery (odds ratio with planned cesarean delivery, 1.16), Dr. Jon F.R. Barrett of Sunnybrook Health Sciences Centre, Toronto, and his colleagues reported on behalf of the Twin Birth Study Collaborative Group.

Another outcome – a composite of maternal death or serious maternal morbidity – also did not differ between the groups, occurring in 7.3% of the cesarean group and 8.5% of the vaginal delivery group. This finding, however, may be explained in part by the high rate of cesarean section in the planned vaginal delivery group, they said (N. Engl. J. Med. 2013;369:1295-305).

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The authors of the Twin Birth Study found "no benefits of planned cesarean section, as compared with planned vaginal delivery, for the delivery of twins between 32 and 38 weeks of gestation..."

Secondary outcomes, including death or a poor neurodevelopmental outcome among the children at 2 years and problematic incontinence among the mothers at 2 years, will be reported subsequently.

Participants in the Twin Birth Study were women between 32 weeks 0 days gestation and 38 weeks 6 days gestation between Dec. 13, 2003, and April 4, 2011, who were pregnant with twins with an estimated weight of between 1,500 g and 4,000 g each and whose first twin was in the cephalic presentation. The women were randomized to planned cesarean delivery or vaginal delivery with cesarean only if indicated and were followed until 28 days after delivery.

Most (90.7%) in the cesarean delivery group delivered by cesarean as planned, and 43.8% in the planned vaginal delivery group required cesarean delivery, the investigators said

The findings are of note because the twin pregnancy rate has increased over time, largely due to assisted reproductive technologies, and the rate of cesarean section for twins also has increased in the wake of studies suggesting a possible benefit of cesarean delivery with respect to perinatal outcomes.

"There are several possible reasons why our results differ from previous observational data: we avoided selection bias, we ensured the presence of an experienced obstetrician at delivery, and many of the twins in our study were born preterm," the investigators said, adding that no significant interaction between treatment group and baseline variables was seen, which suggests that no significant benefit occurred with planned cesarean delivery for any subgroup tested.

"However, our study was not powered for these subgroup analyses. Further study may be warranted for the gestational-age subgroup of 37 to 38 weeks, particularly given the limited number of infants in this subgroup," they said.

Overall, the results of this study are consistent with no more than a 23% reduction and no more than a 74% increase in the odds of fetal or neonatal death or serious neonatal morbidity with planned cesarean vs. planned vaginal delivery, they said.

"In conclusion, we found no benefits of planned cesarean section, as compared with planned vaginal delivery, for the delivery of twins between 32 and 38 weeks of gestation, if the first twin was in the cephalic presentation," they wrote.

This study was supported by a grant from the Canadian Institutes of Health Research. The authors reported having no relevant conflicts of interest.

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