A decade’s experience in primipara, term, singleton, vertex parturients with a sustained low rate of CD

Background: Cesarean delivery (CD) in primiparas with a term singleton vertex fetus (PTSV) is a sentinel event for the future mode of delivery and determinant of repeat CD risk. We aimed to evaluate the risk factors for primary CD in a population with a decade of sustained low rate of intrapartum CD. Methods: This was a retrospective single-center cohort study between 2005 and 2014. The primary outcome of the study was the mode of delivery. PTSV who attempted vaginal delivery were identified and categorized according to the mode of delivery: vaginal delivery vs. CD. Risk factors for intrapartum CD adjusted odds ratio (aOR) [95% confidence interval (CI)] in multivariate analysis were reported. Results: During the study, 121,483 deliveries were registered; 26,301 (21.6%) PTSV were admitted in labor, of which 1944 (7.4%) had an intrapartum CD. Significantly in multivariate analysis, this group had a unique risk profile as compared to those who delivered vaginally; non modifiable risks included advanced maternal age: 3.06 (2.16–4.33), P < 0.001; prior multiple (≥3) miscarriages: 1.94 (1.04–3.62), P = 0.04; low (<6) modified admission cervical score: 2.41 (2.07–2.82), P < 0.001; low birth weight (BW): 1.42 (1.00–2.01), P = 0.05 or macrosomia: 2.38 (1.77–3.21), P < 0.001; modifiable risks included induction of labor: 1.79 (1.51–2.13), P < 0.001 and oxytocin labor augmentation: 8.36 (6.84–10.22), P < 0.001. Conclusion: In a population of PTSV with a sustained low risk for intrapartum cesarean maintained by a strict labor management, induction of labor remains a significant and sole potentially modifiable risk factor for CD.