[Predictors of failed trial of labor in obese nulliparous]

To identify predictors of failed trial of labour (TOL) in obese nulliparous at term.

Retrospective study about 213 nulliparous with a body mass index (BMI) greater than 30kg/m(2) who delivered a vertex singleton after 37 weeks of gestation (WG). Planned caesarean sections were excluded. Maternal, sonographic, per-partum and neonatal characteristics were analyzed according to the mode of entry into labor and delivery route. Univariate and multivariate logistic regression analysis were performed.

The cesarean delivery rate was 28%. Induction of labor (aOR=4.3 [1.8-10.7]), prolonged pregnancy (aOR=10.8 [1.7-67.6]), macrosomia (aOR=5.6 [1.1-27.3]), meconium-stained amniotic fluid (aOR: 2.57 [1.03-6.42]), use of trinitrine (aOR=5.5 [1.39-21.6]) and neonatal head circumference greater than 35cm (aOR=3.1 [1.2-8.0]) were predictors of failed TOL. There was no significant correlation between failed TOL and preconceptional BMI. Univariate analysis revealed an association between excessive weight gain and failed TOL.

Predictors of failed TOL are the same in obese and non-obese women. Preconceptional BMI does not predict failed TOL in this nulliparous obese population.