The epidemiology of labor induction: Arizona, 1997.

OBJECTIVE: This study was undertaken to describe labor induction risk factors and consequences among women with term singleton gestations with vertex presentation. STUDY
DESIGN: Arizona births in 1997 (N = 65,607) were studied by means of stratified analysis and logistic regression.
RESULTS: Labor induction occurred in 20.3% (n = 13,288). Labor induction risk factors were as follows: race or ethnicity (white non-Hispanic 25.3%; Hispanic, 13.9%; foreign-born Hispanic, 10.3%; and US-born Hispanic, 18.5%), education (<12 years, 14.1%; >12 years, 24.6%), payor (private insurance, 24.5%; Medicaid, 16.7%), hospital type (government controlled, 13.7%; investor owned, 30.5%). Race or ethnicity and hospital type remained important determinants of labor induction in the multivariate analysis. Relative risks of cesarean delivery with labor induction were as follows: nulliparous, 1.38; parous with no previous cesarean delivery, 1.00; and parous with previous cesarean delivery, 0.50.
CONCLUSION: Large variations in labor induction were noted across maternal ethnicity and hospital type categories. Labor induction increased cesarean delivery rates among nulliparous women, whereas no increase was seen among parous women with no previous cesarean delivery. Labor induction was used less often among those with previous cesarean delivery; when it was used in this group, however, it was associated with a lower cesarean delivery rate.