Prolongation of active second stage of labor: Associated factors and perinatal outcomes.

Background: Current data does not allow to define a reasonable threshold of duration of active second stage (ASS) of labor beyond which a medical intervention should be considered. Primary objective was to analyse perinatal outcomes associated with prolonged ASS beyond 45 min. Secondarily, we analysed associated maternal, gestational, labor and delivery characteristics associated with prolonged ASS.

Methods: We performed a monocentric retrospective study among women with vaginal delivery, a term singleton cephalic fetus, without history of cesarean section. We compared women with active second stage of labor longer than 45 min (ASS ≥45 min, group A) and women with instrumental vaginal delivery (IVD) only for failure to progress (FtP) before 45 min of pushing (group B). Primary outcome was postpartum hemorrhage (PPH). Maternal and neonatal outcomes associated with ASS ≥ 45 min were assessed with multivariable logistic regression models.

Results: Prolonged ASS ≥45 min (group A, N=177) was associated with lower rate of persistent occiput posterior position (1.7 vs 9.5%, p<0.01) and of non-engaged presentation when expulsive efforts started (10.7 vs 27.4%, p<0.01), compared to IVD for FtP <45 min (group B, N=84). In group A, 52% of women had instrumental delivery. Prolonged active second stage was independently associated with lower odds of episiotomy (38.4 vs 61.9%, AOR(95%CI)=0.43[0.24-0.78]) and was not associated with PPH (5.1 vs 5.9%, AOR=1.01[0.28-3.68]), pH<7.20, 5-min Apgar score < 7 (20.2 vs 15.9%, AOR=2.00[0.89-4.48]), lactates > 6 (23.0 vs 24.3, AOR=1.45[0.68-3.07]) or transfer to neonatal intensive care unit (6.2 vs 2.4%, AOR=4.71[0.76-29.08].

Discussion: Extending the duration of active second stage of labor beyond 45 min seems reasonable under rigorous surveillance of maternal and fetal wellbeing.