Effect of Preeclampsia, Magnesium Sulfate Prophylaxis, and Maternal Weight on Labor Induction: A Retrospective Analysis

Background: Our purposes were to determine the effect of preeclampsia, magnesium sulfate prophylaxis, and maternal weight on labor induction in women with preeclampsia and identify risk factors associated with its failure. Methods: Fifty-five preeclamptic women and 176 non-preeclamptic women requiring labor induction over an 18-month period were studied retrospectively. Prostaglandin E2 (dinoprostone) and oxytocin were used for labor induction. Women with rupture of the membranes, spontaneous contraction resulting in cervical change, or an initial cervical examination showing more than 2 cm dilatation and 50% effacement were excluded. Statistics were analyzed with χ2 test, Fisher’s exact test, Student t test, Mann-Whitney U test, and multiple logistic regression. Results: The women with preeclampsia had a significantly higher rate of failed induction than did those without preeclampsia (p = 0.01). However, the women with preeclampsia had a higher mean maternal weight and an increased use of magnesium sulfate, and labor was induced at earlier gestational age than in those without preeclampsia (p < 0.05 for each). Multiple logistic regression showed that the use of magnesium sulfate, higher maternal weight, and unfavorable cervix, but not preeclampsia, were significantly associated with an increased risk of failed induction after correction for known confounding variables. Conclusions: Although the risk of failed induction is increased in preeclamptic women, preeclampsia is not an independent risk factor for failed induction. The use of magnesium sulfate, higher maternal weight, and unfavorable cervix are independent risk factors for failed induction.