Cesarean delivery of twins between 32 weeks and 38 weeks, 6 days' gestation did not significantly decrease or increase the perinatal mortality or serious neonatal morbidity rates, according to the results of a large randomized trial.1
While the researchers confirmed previous studies by finding a higher risk of an adverse perinatal outcome for the second twin than for the first twin, this study also found that planned cesarean section did not reduce that risk either.
“There has been controversy regarding the safest method for the delivery of twins at or near term,” the study authors wrote, citing previous studies such as the Term Breech Trial, that have showed reduced risk with planned cesarean delivery.
“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 authors concluded.
The trial, which was supported by a grant from the Canadian Institutes of Health Research and was centrally controlled at the Centre for Mother, Infant, and Child Research at the Sunnybrook Health Sciences Centre in Toronto, enrolled a total of 1398 women (2795 fetuses) who were randomly assigned to planned cesarean delivery and 1406 women (2812 fetuses) who were assigned to planned vaginal delivery. Women were enrolled from 25 countries, and it took 7.5 years to recruit the participants. More than 96% of all the first twins were in the cephalic presentation.
Even among those assigned to the planned-vaginal-delivery group, 43.8% underwent cesarean. For the planned-cesarean-delivery group, 90.7% of the women had a cesarean.
When the researchers evaluated the primary outcome of perinatal mortality and serious morbidity between the two groups, they found no significant difference. Specifically, the primary outcome occurred in 2.1% of those in the planned-cesarean-delivery group and 1.9% in the planned-vaginal-delivery group (odds ratio with planned cesarean, 1.16; 95% confidence interval, 0.77 to 1.74; P=0.49).
In addition, the risk of maternal death or serious morbidity was not significantly different between the two groups (7.3% in the planned-cesarean-delivery group vs 8.5% in the planned-vaginal-delivery group).
Those assigned to deliver via cesarean section also delivered earlier than those in the planned-vaginal-delivery group (mean number of days from randomization to delivery, 12.4 vs 13.3, respectively; P=0.04).
“The rise over time in the national rate of cesarean delivery has been well documented. Less well documented has been the rise in the national rate of cesarean delivery for twins, from 53.9% of twin deliveries in 1995 to 75.0% in 2008,” noted Michael F. Greene, MD, in an accompanying editorial.2 “Although the national perinatal mortality rate has fallen steadily during this time, from 14.6 deaths per 1000 births in 1985 to 10.5 deaths per 1000 births in 2006, it remains legitimate to ask whether all those cesarean deliveries were necessary to ensure the lowest possible maternal and perinatal morbidity and mortality.”
Greene predicted that the results of the study are unlikely to lead to a change the use of cesarean delivery for twins nationwide.2
- Cesarean delivery did not significantly decrease or increase the perinatal mortality or serious neonatal morbidity rates among twins born between 32 weeks and 38 weeks, 6 days gestation.
- Planned cesarean does not reduce the risk of increased adverse events for the second twin.
- The report comes as cesarean rates continue to rise with the birth of twins, but it is unclear if the trial will affect a change in practice.
1. Barrett JFR, Hannah ME, Hutton eI, et al, for the Twin Birth Study Collaborative Group. A randomized trial of planned cesarean or vaginal delivery for twin pregnancy. N Engl J Med. 2013;369:1295-1305.
2. Greene MF. Delivering twins. N Engl J Med. 2013;369:1365-1366.