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Am Fam Physician. 2006;74(8):1411-1412

The incidence of vaginal birth after cesarean delivery (VBAC) in the United States has steadily declined after reaching a peak of 27.4 percent of all deliveries in 1997. The American College of Obstetricians and Gynecologists (ACOG) revised its VBAC guidelines in 1999, recommending for the first time that VBAC only be performed in “institutions equipped to respond to emergencies with physicians immediately available to provide emergency care.” Rural hospitals may have been affected by this new guideline; however, it is uncertain if adverse maternal and neonatal outcomes were reduced after the revision. Zweifler and colleagues conducted a retrospective analysis of birth data to determine if the ACOG guideline change affected neonatal and maternal mortality.

The study population consisted of 386,232 women who previously had a cesarean delivery for a singleton birth in a California hospital between 1996 and 2002. Data were collected from the California Department of Health Services Birth Statistical Master Files. Data from before the guideline revision (1996 to 1999) were compared with data from after the revision (2000 to 2002). Neonatal deaths were defined as newborns living fewer than 28 days, and maternal deaths were defined as deaths within 72 hours of delivery. The total number of attempted VBAC deliveries (successful and unsuccessful) also was noted.

Although there was a significant decrease in attempted VBAC deliveries after the ACOG guideline revision (24 percent of all deliveries before the revision to 13.5 percent after), neonatal and maternal mortality rates did not change. During both periods, neonatal mortality rates for attempted VBAC deliveries were similar to those for repeat cesarean deliveries, except for infants with a very low birth weight (i.e., less than 1,500 g). Neonatal mortality rates for infants with a very low birth weight were higher for attempted VBAC than for repeat cesarean deliveries during both periods. Maternal death rates did not change significantly after the guideline revision, regardless of delivery type.

The authors conclude that the ACOG guideline revision resulted in a large decline in the percentage of women in California who attempted VBAC, but that it did not improve neonatal or maternal mortality rates. In addition, neonatal mortality in infants weighing more than 1,500 g was not related to delivery type. The authors suggest that pregnant women who have had a previous cesarean delivery be informed about these encouraging findings in addition to the risks associated with VBAC.

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