To investigate mode of birth in relation to onset of labor and Bishop score.

Retrospective observational cohort design.

A 434-bed Magnet e-designated community hospital.

Nulliparous women, 18 years of age or older, who gave birth at 37 to 41 weeks gestation to live, singleton fetuses in the vertex presentation (N = 701).

We conducted a retrospective chart review and used chi-square analysis to measure the associations among mode of birth, onset of labor, and Bishop score. We used logistic regression to test the probability of cesarean birth for women undergoing elective induction of labor.

Most participants (n = 531, 75.7%) gave birth vaginally. Significant findings included the following relationships: spontaneous onset of labor and vaginal birth (χ2 = 22.2, Ø = 0.18, p < .001) and Bishop score of greater than or equal to 8 and vaginal birth (χ2 = 4.9, Ø = .14, p = .028). Induction of labor was a significant predictor in cesarean birth when controlling for age and body mass index (OR = 2.1, 95% confidence interval [1.5, 3.1], p < .01).

Reducing elective induction of labor in women with low-risk pregnancies may help lower the risk of cesarean birth. Clinically, Bishop score and mode of birth have a weak association, particularly when induction includes cervical ripening.