Predicting success of labor induction in singleton term pregnancies by combining maternal and ultrasound variables

To assess pre-induction maternal and ultrasonographic factors in the prediction of the onset of labor within 12 h, and vaginal delivery (VD) irrespective of the induction-to-delivery interval in term pregnancies.

We performed a prospective cohort study with 204 singleton pregnant women between 37 and 42 weeks of gestation. The following maternal and ultrasonographic variables were assessed: parity, marital status, height, body mass index (BMI), previous cesarean section (Cs), Bishop score, variety of fetal position, single deepest pocket (SDP), fetal middle cerebral and umbilical artery resistance indices, cervical length (CL) measurement, posterior cervical angle (PCA), head circumference (HC) and estimated fetal weight (EFW). χ(2) test and logistic regression analysis were applied to compare the groups. Receiver operating characteristics (ROC) curves were determined.

VD occurred in 116 (56.9%) women. Prediction of the onset of labor within 12 h was provided by the BMI and resistance index of the fetal middle cerebral artery. Prediction of the VD irrespective of the induction-to-delivery interval was provided by height, BMI, parity, number of prenatal visits, consistency, effacement and dilation of uterine cervix, PCA, oligohydramnios, HC and EFW. Area under ROC curve for PCA and EFW were 63.5 (sensibility: 66.4%, specificity: 59.1%) and 60.2 (sensibility: 54.3%, specificity: 70.4%), respectively.

Several pre-induction maternal and ultrasonographic factors can increase the chance of achieving a successful VD. PCA and EFW were the best ultrasonographic predictors for the success of induction of labor; however, with limited potential to be used in the clinical practice.