Shoulder dystocia at noninstrumental vaginal delivery.

This study examines the relationship between episiotomy and the occurrence of shoulder dystocia among noninstrumental vaginal deliveries. Analysis of data from a retrospective database was used to study noninstrumental vaginal deliveries in New Jersey during the years 1996 to 2001. The episiotomy group and nonepisiotomy group were analyzed separately using univariate and multivariate analysis. Among 358,664 deliveries, rate of shoulder dystocia was 1.0% (n = 3596). Thirty-five percent of deliveries were assisted by episiotomy. Rate of dystocia was 1.42% with the use of episiotomy, and 0.81% when episiotomy was not used. This increased rate with episiotomy was noted across all of the racial groups, all birthweight categories, and all of the risk factor subgroups analyzed. There was a gradual decrease in the use of episiotomy from 37.30 to 26.03% without a corresponding increase in the rate of dystocia. Among noninstrumental deliveries, the rate of shoulder dystocia is higher in the episiotomy group. Decrease in the use of episiotomy has not resulted in an increase in the occurrence of dystocia.