Objective: To 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.
Methods: Cervical 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.
Results: A 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).
Conclusion: Only 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.
(C) 1996 The American College of Obstetricians and Gynecologists