ObjectiveTo evaluate maternal parity, the sonographic measurement of cervical length, and the five components of the Bishop score to determine which factors best predict the length of latent-phase labor in women undergoing labor induction.MethodsCervical position, cervical consistency, cervical effacement, cervical dilation, station of fetal presenting part, maternal parity, and sonographic measurement of cervical length were studied prospectively in 109 women undergoing labor induction. A multiple regression model was used to determine which factors best predict the length of latent-phase labor.ResultsA model using these seven factors was predictive in determining the number of hours of latent-phase labor (F= 32.1,P< .001). Backward stepwise multiple linear regression indicated that only cervical dilation independently predicted the length of latent-phase labor. There was a significant correlation between the clinical assessment of cervical effacement and the sonographic estimation of cervical length, (r= −0.523,P< .001).ConclusionOnly cervical dilation appears to predict the length of latent-phase labor. The sonographic evaluation of cervical length and maternal parity do not add significant independent information.