Vaginal delivery for preterm vertex babies not as risky as thought

By Piriya Mahendra, MedWire Reporter

Vaginal delivery for early preterm infants who have a vertex presentation does not have a significant negative impact on neonatal mortality compared with cesarean delivery, research suggests.

However, for breech births, the failure rate of vaginal delivery was high and planned caesarean delivery was significantly associated with lower neonatal mortality, report Uma Reddy (National Institute of Child Health, Bethesda, Maryland, USA) and team in the American Journal of Obstetrics & Gynecology.

"Selecting a route of delivery at less than 32 weeks' gestation is a difficult clinical decision given the high rate of infant mortality and morbidity as well as the maternal risks associated with cesarean delivery," she said in a press statement.

"For vertex-presenting fetuses less than 32 weeks' gestation, we saw no improvement in neonatal mortality with a planned cesarean delivery."

Their study of 2906 singleton pregnancies found that attempting vaginal delivery at 24‑26 weeks' gestation did not significantly affect neonatal mortality and had a success rate of 84%. However, when the fetal presentation was breech, only 27.6% of vaginal births were successful and neonatal mortality was significantly higher than in cesarean deliveries, at 25.2% versus 13.2%.

At 28‑31 weeks' gestation, nearly half of the mothers whose babies had a vertex presentation and attempted vaginal deliveries had successful births, and there was no significant difference in the mortality rate compared with those who had a planned cesarean delivery. However, for breech fetuses, neonatal mortality was 6.0% in those with vaginal deliveries compared with only 1.5% in women who had cesarean deliveries.

The researchers used data from the Consortium on Safe Labor, which comprises information on over 200,000 deliveries between 2002 and 2008 from 12 clinical centers and 19 hospitals across the USA.

Maternal or fetal indications, defined as preeclampsia, placental abruption, or severe maternal medical disease were responsible for 45.7% of early preterm deliveries (24‑26 weeks' gestation) between 2002 and 2008 in the USA. Preterm premature rupture of membranes was responsible for 37.7% of early preterm births, and preterm labor for 16.6%.

Reddy pointed out that previous studies examining the effect of delivery route on neonatal mortality for early preterm births analyzed the actual rather than attempted route of delivery.

"The detailed information in our study, not available in birth certificate data, enabled us to account for the effect of attempted route of delivery and indications for delivery on neonatal mortality," she said.

"This information has direct clinical applications and is crucial for counseling families about the benefits and risks of attempting vaginal delivery in this situation."

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