PROLONGED LABOR IN NULLIPARAS - LESSONS FROM THE ACTIVE MANAGEMENT OFLABOR

Objective: To define factors causing prolonged labor in nulliparous wo men undergoing active management of labor. Methods: We included all nu lliparas delivered during 1990-1994 with spontaneous onset of labor la sting more than 12 hours, singleton gestation, cephalic presentation, and labor at greater than 37 weeks. Each patient was matched with the next nulliparous woman who delivered with a labor lasting less than 12 hours and who fulfilled the same inclusion criteria. Subjects were ma naged according to the previously described active management of labor protocol from The National Maternity Hospital, Dublin. Results: In th e 5-year period, 9018 nulliparas met inclusion criteria, with 147 (1.6 %) having prolonged labor. Prolonged labor was due to inefficient uter ine action in 65%, persistent occipitoposterior position in 24%, and c ephalopelvic disproportion in 11% of cases. Univariate analysis showed statistically significant (P <.05) differences in maternal body mass index, cervical dilation on admission, oxytocin use, epidural use, pla cement of epidural at less than 2 cm of dilation, and birth weight bet ween these study groups. On multivariate conditional logistic regressi on analysis, the following were significant independent predictors for having a prolonged labor (odds ratios with 95% confidence intervals p resented): 3.1 (1.3-7.3) for cervical dilation less than 2 cm on admis sion, 42.7 (7.5-242.0) for early epidural placement, 5.1 (1.9-13.7) fo r epidural placement at greater than or equal to 2 cm, and 10.2 (3.6-2 9.4) for birth weight greater than 4000 g. Conclusion: Less-advanced c ervical dilation on admission and epidural use, especially when placed early, are strongly associated with prolonged labor.