Risk Factors for Cesarean Delivery after Induction of Labor in Nulliparous Women with an Unfavorable Cervix at or beyond 41 Weeks of Gestation

AIMS: To investigate risk factors for cesarean section (CS) following labor induction in nulliparas with an unfavorable cervix at or beyond 41 weeks of gestation. METHODS: In this retrospective cohort study, a total of 276 nulliparas with an unfavorable cervix (Bishop score ≤6) who underwent labor induction for prolonged pregnancies were included out of a total of 646 patients who delivered ≥41 weeks (2002-2011). RESULTS: 82 (29.7%) patients of the 276 delivered by CS. The patients who underwent CS had less cervical dilatation and a lower Bishop score on admission than those patients who delivered vaginally (0.76 ± 0.47 vs. 0.92 ± 0.58 cm, p = 0.03 and 1.16 ± 1.25 vs. 1.51 ± 1.34, p = 0.04, respectively). Neonatal birth weight and biparietal diameter (BPD) were significantly smaller in the vaginal delivery group (3,414.93 ± 361.37 vs. 3,534.81 ± 383.05 g, p = 0.01 and 9.43 ± 0.35 vs. 9.65 ± 0.42 cm, p < 0.01). After multiple logistic regression analysis, maternal height, BPD, and early rupture of membranes (ROM) were independently related with CS. Early ROM was defined as spontaneous ROM that occurred before the onset of the active phase of labor. CONCLUSION: Maternal height, BPD, and early ROM were risk factors for CS following labor induction in nulliparas at or beyond 41 weeks of gestation.ope