Abstract
Objective We sought to evaluate differences in pregnancy outcomes following early amniotomy
in women with class III obesity (body mass index ≥40 kg/m2) undergoing induction of labor.
Study Design This is a retrospective cohort study of women with class III obesity undergoing term
induction of labor from January 2007 to February 2013. Early amniotomy was defined
as artificial membrane rupture at less than 4 cm cervical dilation. The primary outcome
was cesarean delivery. Secondary outcomes included length of labor, a maternal morbidity
composite, and a neonatal morbidity composite. A subgroup analysis examined the effect
of parity. Multivariable logistic regression was used to adjust for covariates.
Results Of 285 women meeting inclusion criteria, 107 (37.5%) underwent early amniotomy and
178 (62.5%) underwent late amniotomy. Early amniotomy was associated with cesarean
delivery after multivariable adjustments (adjusted odds ratio [aOR], 2.05; 95% confidence
interval [CI], 1.21–3.47). There were no significant differences in length of labor
or maternal and neonatal morbidity between groups. When stratified by parity, early
amniotomy was associated with increased cesarean delivery (aOR, 3.10; 95% CI, 1.47–6.58)
only in nulliparous women.
Conclusion Early amniotomy among class III obese women, especially nulliparous women, undergoing
labor induction may be associated with an increased risk of cesarean delivery.
Keywords
amniotomy - induction of labor - obesity - cesarean delivery
