Increasing rates of operative vaginal delivery across two decades: accompanying outcomes and instrument preferences.

OBJECTIVE: To examine rates and outcomes of operative vaginal delivery over a 20-year study period and the changing preference for various instruments during this period.

STUDY DESIGN: This retrospective analysis of prospectively gathered data was carried out at a large tertiary referral center from 1991 to 2010. All cases of operative vaginal delivery during the study period were recorded. The rates of instrumental delivery, as well as neonatal outcomes and instrument preference, were compared for individual 5-year epochs.

RESULTS: During the study period there were 156,130 deliveries of which 17,841 were operative vaginal deliveries, an incidence of 11.4/100 deliveries and 13.6/100 vaginal deliveries. There was an increase in the rate of operative vaginal delivery across the 20-year period (P < 0.0001; R(2) = 0.85; Slope = 0.42). When individual 5-year epochs were compared, the incidence of instrumental delivery increased from 7.3% (2340/31,937) in the first five years, 1991-1995, to 13.7% (6179/45,177) in the final five years, 2006-2010 (P < 0.0001; OR 2.34, 95% CI = 2.23-2.47). The perinatal mortality rate in cases of instrumental delivery was decreased when these time periods were compared (7.3/1000 (17/2340) vs. 1.8/1000 (11/6179); P = 0.003, OR 0.24, 95% CI = 0.11-0.52). The choice of instrument also varied, with 68.2% (1596/2340) of instrumental deliveries in 1991-1995 being carried out with forceps compared to 32.9% (2033/6179) in 2006-2010 (P < 0.001).

CONCLUSION: Rates of operative vaginal delivery have increased over the 20-year study period. The rate of perinatal mortality in infants who had an assisted vaginal delivery was decreased in the 5-year epoch at the end of the study compared with the period at the beginning. The rate of forceps delivery has fallen significantly, with vacuum delivery now being the choice of the majority of clinicians.