Abstract
This study was done to evaluate transvaginal ultrasonographic measurement of cervical length at 20 to 24 weeks and 37 weeks as a predictor of prolonged pregnancy (defined as a pregnancy that extended beyond 41+2 weeks of gestation [289 days]) in nulliparous women. This prospective observational study enrolled 149 consecutive nulliparous women with singleton gestation at 37 weeks. Cervical length was measured by transvaginal ultrasonography at 20 to 24 weeks and 37 weeks. Cervical length at 37 weeks, but not at 20 to 24 weeks, was significantly longer in women delivered at >41+2 weeks than in those delivered at