[Risks factors of cesarean delivery after 3hours of delayed pushing]

Identify the factors associated with caesarean delivery for unengaged fetal head beyond 3hours of passive second stage of labor, among primiparous patients.

A case-control study conducted in level III universitary center between October 2012 and September 2015. Only primiparous at term, with a singleton, cephalic fetus and a passive second stage of labor prolonged over 3hours before pushing were included. During the second stage of labor, patients who had caesarean for abnormal fetal heart rate were excluded. Risk factors of cesarean were analyzed with univariate analysis and after statistical adjustment using multivariate logistic regression.

The mean passive second stage duration was significantly longer among patients who had a caesarean (3h37±21min vs 3h13±19min [P=0,0001]). After multivariate logistic regression, factors associated with a risk of caesarean were body mass index higher than 30kg/m² (OR=25.9 [3.1-215.9]). fetal macrosomia suspected by 3rd trimester ultrasound (OR=4.4 [1.2-16.4]), induction by prostaglandins (OR=5.7 [2.1-15.5]), a stagnation of cervical dilatation during the 1st stage (OR=[1.3-6.8]), and fetal occiput posterior position beyond 3hours (OR=30.7 [3.3-280.9]).

Risk of caesarean delivery for unengaged fetal head beyond 3hours of passive second stage of labor is associated with maternal, fetal and obstetrical factors. Those factors might be taken into account before accept or not a 3rd hour at full cervical dilation.