ObjectiveEvaluation of factors influencing the duration of second-trimester pregnancy interruption with vaginal misoprostol for fetal abnormality.MethodsAll medical terminations ≥13 weeks of gestation 1/1997 to 12/2007 were prospectively identified. Cases receiving vaginal misoprostol 400 µg 6-hourly were extracted from the database and outcomes reviewed.ResultsThis consecutive case series comprised 1066 women. Median maternal age was 31 years [interquartile range (IQR) 26, 36] and 15.4% had at least one prior cesarean delivery. Principal indications for termination were aneuploidy (37.6%), neural tube defects (15.9%) and cardiac anomalies (9.4%). Median gestation at termination was 19.5 weeks (IQR 17.9, 21). Median abortion interval was 16.1 h (IQR 12, 23.5). Lower maternal age (median duration 17.6 vs 15.2 vs 13.6 h, age <30 vs 30–39 vs > 40 years, p <0.001), nulliparity (median duration 19 vs 14.3 h, nulliparous vs parous, p <0.001) and increasing gestation (median duration 13 vs 17.8 h, 20 weeks, p <0.001) were associated with abortion prolongation. Controlling for gestation, age and parity, apart from musculoskeletal abnormalities (associated with abortion prolongation, p = 0.03), the specific fetal anomaly did not influence duration.ConclusionsThree factors: nulliparity, younger maternal age and increasing gestation, were associated with abortion prolongation. Apart from musculoskeletal abnormalities, the fetal anomaly had no impact on abortion duration. Copyright © 2009 John Wiley & Sons, Ltd.