Vaginal Delivery for Early Preterm Birth Is Safe

With the exception of breech presentations, attempting vaginal delivery of early preterm fetuses in the vertex position is highly successful and associated with neonatal mortality rates similar to those for cesarean delivery, according to new study findings.¹

Researchers used data from the Consortium on Safe Labor (CSL), which was a retrospective study that collected detailed information on more than 200,000 deliveries between 2002 and 2008 from 12 clinical centers and 19 hospitals throughout the United States. Preterm labor, preterm premature rupture of membranes (PPROM), and maternal or fetal issues (eg, preeclampsia, placental abruption, and severe maternal medical disease) were categorized as indications for preterm delivery. Most preterm deliveries occurred because of maternal or fetal indications (45.7%), with preeclampsia and major congenital anomalies being the leading contributors, PPROM (37.7%), and preterm labor (16.6%).

To account for the fact that neonatal mortality and morbidity is highest when delivery occurs between 24 0/7 weeks and 27 6/7 weeks, researchers separately analyzed data using gestational age blocks. The first block was for deliveries that occurred between 24 0/7 weeks and 27 6/7 weeks, and the second block was for those between 28 0/7 and 31 6/7 weeks.

More than 80% of attempted vaginal births in the earliest delivery group (24 to 27 weeks) were successful and had no significant affect on neonatal mortality. However, only 27.6% of attempted vaginal deliveries were successful when the fetus was in a breech presentation.

In deliveries that occurred between 28 and 31 weeks’ gestation, a breech presentation was associated with a higher rate of neonatal mortality in vaginal deliveries compared with cesarean deliveries (6% vs 1.5%, respectively). However, there were no differences in the rates of neonatal mortality between vaginal deliveries and cesarean deliveries when the fetus was in a vertex position.

This is the first study to evaluate outcomes for actual route of delivery and not attempted route of delivery, say the study authors. These findings also provide physicians with crucial information about the risks and benefits of vaginal delivery that they can share with patients in very early term labor.

Pertinent Points:
- Attempting vaginal deliveries when the fetus is in a vertex position at 24 to 27 weeks of gestation did not significantly affect neonatal mortality.
- More than 80% of attempted vaginal deliveries at 24 to 27 weeks’ gestation were successful.
- When the fetus is in a breech presentation, the failure rate of attempted vaginal deliveries is high; planned cesarean delivery in this population was associated with lower rates of neonatal mortality.

References:

1. Reddy UM, Zhang J, Sun L, et al. Neonatal mortality by attempted route of delivery in early preterm birth. Am J Obstet Gynecol. 2012;207:117.e1-117.e8.