Neonatal mortality by attempted route of delivery in early preterm birth

Fifty four percent of all infant deaths in the United States occur among the 2 percent of infants born at less than 32 weeks’ gestation (2007).1 The optimal route of delivery for the early preterm fetus remains controversial. Some observational studies have shown a lower neonatal mortality for planned cesarean delivery as compared with vaginal delivery for vertex 2–4 and breech early preterm pregnancies 2, 4–9whereas other studies do not show a difference by route of delivery for vertex10–12 or breech presentation.13–15

The vertical uterine incision often required for cesarean delivery at this gestational age increases the risks of hemorrhage, bladder injury and other complications. There is also an increased risk of uterine rupture, placenta previa and placenta accreta in subsequent pregnancies.16–17

Six trials have attempted to randomize the route of delivery for women in preterm labor at high risk for delivery. Recruitment difficulties limited combined enrollment in all of these trials to only 122 women. A metaanalysis of these trials found no statistically significant differences in neonatal outcomes by route of delivery, except for lower cord pH values among infants delivered by cesarean delivery.18

Because randomized trials to answer this question have not proven feasible, a study using recent cohort data to determine the effect of fetal presentation, gestational age, and the intended route of delivery on outcome would be valuable. Therefore, the purpose of this study was to use a contemporary cohort that reflects current obstetric and neonatal clinical practice to identify the precursors of early preterm delivery ≤ 32 weeks of gestation and to assess the effect of intended route of delivery on neonatal mortality for viable singleton early preterm births, stratified by presentation.

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