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.
Address reprint requests to: William J. Watson, MD, Department of Perinatal Medicine, Sioux Valley Hospital, 1201 South Euclid Avenue, Suite 204, Sioux Falls, SD 57105
© 1996 The American College of Obstetricians and Gynecologists