Elective induction versus spontaneous labor: a case-control analysis of safety and efficacy

To investigate the incidence, efficacy, and safety of elective induction in a community teaching hospital over 1 year.

This is a retrospective case-control study of rate, safety, and efficacy of all term inductions with vertex presentations judged to be elective by chart analysis. Cases were matched one for one for age, parity, and pay status with controls in spontaneous labor. The elective induction women were compared with those in spontaneous labor using chi2 Student t test, and Fisher exact test. Potential risk factors for cesarean delivery and neonatal intensive care unit (NICU) admission were then selected and subjected to bivariate analysis. Stepwise logistic regression was applied to control for confounding and to select which risk factors were important for those end points.

There were 461 case-control pairs. The elective induction rate was 12.3%. Cesarean delivery was increased by elective induction in bivariate analysis (odds ratio [OR]=1.81, confidence interval [CI]=1.07, 3.08; power=.60). The cesarean delivery rate was 8.7% (control 5.0%). In a multiple regression model of potential risk factors for cesarean delivery, nulliparity (OR=6.14, CI=2.90, 13.04), cervical priming (OR=3.06, CI=1.46, 6.40), oxytocin usage (OR=2.82, CI=1.03, 7.75), gestational age at least 287 days (OR=2.51, CI=1.38, 4.58), and birth weight at least 3800 g (OR=2.29, CI=1.27, 4.13) were significant, but elective induction and epidural anesthesia were not. Elective induction did not significantly increase the rate of NICU admission (4.6% versus control 3.9%). In a multiple regression model of potential factors predicting NICU admission, only a 5-minute Apgar score of at most 8 was significant (OR = 12.34, CI=6.01, 25.3).

Elective induction is commonly practiced, safe, and efficacious. Cesarean delivery is increased significantly by nulliparity and/or an unfavorable cervix, among other factors, but not by elective induction itself.