Prediction of successful induction of labour by pre-induction sonographic measurement of cervical length and parity

Abstract

We aimed to examine the effect of parity on the relationship between preinduction sonographically measured cervical length, the induction to delivery interval and prediction of successful vaginal delivery within 24 hours. In this multicentre study, preinduction cervical assessments were undertaken in 696 women with singleton pregnancies and cephalic presentation at 34–42 weeks of gestation. Of these 337 were nulliparae and 359 were multiparae. The Bishop score was assessed by digital examination and the cervical length was measured by transvaginal sonography. Grouped linear regression analysis demonstrated that cervical length and parity provide significant independent contributions in the prediction of induction to delivery interval for nulliparae and multiparae. The Kaplan–Meier survival curves indicated the likelihood of delivering within 24 hours. Futhermore, along with the Kruksal–Wallis test for analysis of variance, the survival curves showed that at a cervical length of less than 30 mm, multiparae with a cervical length 10 mm longer than nulliparae have a similar induction to delivery interval.