Objective: To examine the association of prolonged latent phase with cesarean risk, subsequent labor abnormalities, and other adverse maternal and neonatal outcomes.
Methods: Patients with prolonged latent phase were compared to patients with normal latent phase. We studied 10,979 singleton vertex deliveries of at least 37 weeks' gestation. Patients with risk factors for adverse outcome known before labor were excluded from the analysis.
Results: Seven hundred thirteen patients (6.5%) had prolonged latent phase. Subsequent labor abnormalities were more frequent among patients with prolonged latent phase (42.9 versus 16.3%; P < .05), as was cesarean delivery (24.4 versus 6.9%; P < .05). Need for neonatal resuscitation, thick meconium, maternal fever, low 5-minute Apgar score, intensive care nursery admission, lengthened maternal and newborn hospital stays, and higher estimated blood loss were all significantly more frequent in patients with prolonged latent phase after controlling for mode of delivery. Multivariate linear logistic regression models were created to determine whether these risks actually reflected the prolonged latent phase. The first model controlled for other labor abnormalities, parity, epidural use, and macrosomia and showed prolonged latent phase to be associated with an increased risk for cesarean delivery (relative risk [RR] 1.65, 95% confidence interval [CI] 1.32-2.06). The second model controlled for other labor abnormalities, postdates, thick meconium, mode of delivery, and prolonged rupture of membranes and showed that both the need for newborn resuscitation and 5-minute Apgar scores less than 7 were significantly more frequent in association with a prolonged latent phase (RR 1.37 and 1.97, 95% CI 1.15-1.64 and 1.23-3.16, respectively).
Conclusions: Prolonged latent phase is independently associated with an increased incidence of subsequent labor abnormalities, need for cesarean delivery, depressed Apgar scores, and need for newborn resuscitation. The presence of prolonged latent phase should alert the clinician to an increased risk for further problems during the labor.