Objective: To examine the effect of labor induction length on maternal and neonatal outcome.
Methods: Inductions of labor were reviewed retrospectively, comparing 27 patients with infectious complications to 313 with no infections. Univariate analysis, t-test, chi2, and Fisher exact test were used for statistical analysis. Forward stepping logistic regression was used in a multivariate model to identify odds ratio (OR) and 95% confidence intervals (CI).
Results: There was a statistically significant increased risk of maternal infection with increasing induction time. In univariate analysis, cesarean delivery, duration of induction, duration of oxytocin administration, nulliparity, use of internal monitors, increased maternal weight gain, and low cervical dilatation at start of induction were all associated with increased maternal infection risk. Multivariate analysis showed duration of induction for each additional 2 hours (OR 1.09; 95% CI 1.01, 1.18) and nonwhite ethnicity (OR 5.95; 95% CI 1.72, 20.49) to be associated significantly with maternal infection. Maternal infection was associated with lower Apgar scores and increased neonatal intensive care unit admissions. In patients who delivered vaginally, a logistic regression model estimated infectious morbidity at 40 hours to be 10%. The cesarean rate was not increased with prolonged induction.
Conclusion: Prolonged induction is associated with a small increased risk of infectious morbidity, with an estimated 10% incidence noted after 40 hours of induction in women who deliver vaginally.