Mode of delivery in a subsequent pregnancy following previous instrumental delivery

Objective: To assess mode of subsequent delivery in women with previous instrumental vaginal delivery. Study design: In this retrospective longitudinal study we followed women who underwent instrumental delivery. The study group included all consecutive parturient women who underwent an instrumental vaginal delivery during a 24-month period (1996-1999). We then identified women who had a subsequent delivery in our center until the end of the year 2010. The control group included women who had a spontaneous vaginal delivery from the same time. Results: During the index period we had 349 consecutive successful instrumental vaginal deliveries. Of those, 125 women had a subsequent delivery in our center (35.8%). In subsequent pregnancies, the spontaneous vaginal delivery rate was 76.8% and 90.4%; the instrumental delivery rate was 8.8% and 1.6%; and the cesarean rate was 14.4% and 8.0%, in the instrumental delivery, and spontaneous vaginal delivery groups, respectively (P<0.05). The odds ratio for a woman to undergo either an instrumental delivery or a cesarean after having an instrumental delivery in a previous pregnancy was 2.8 (95% confidence interval 1.4-5.9, P<0.05). Conclusion: Women with a previous instrumental delivery are at an increased risk of requiring either an instrumental delivery or a cesarean section in a subsequent pregnancy compared with women with a previous spontaneous vaginal delivery.