Interrelations between four antepartum obstetric interventions and cesarean delivery in women at low risk: a systematic review and modeling of the cascade of interventions.

Objectives: To critically appraise the literature on the relations between four intrapartum obstetric interventions-electronic fetal monitoring (EFM), epidural analgesia, labor induction, and labor acceleration; and two types of delivery-instrumental (forceps and vacuum) and cesarean section.

Methods: This review included meta-analyses published between January 2000 and April 2012 including at least one randomized clinical trial published after 1995 and presenting results on low-risk pregnancies between 37 and 42 weeks of gestation, searched in the databases Medline, Cochrane Library, and EMBASE with no language restriction.

Results: Of 306 documents identified, 8 fulfilled the inclusion criteria and presented results on women at low risk. EFM at admission (vs intermittent auscultation) was associated with cesarean delivery (odds ratio [OR] = 1.20, 95% confidence interval [CI] 1.00-1.44) and epidural analgesia (OR = 1.25, 95% CI 1.09-1.43). Epidural on request was associated with cesarean delivery (OR = 1.60, 95% CI 1.18-2.18), instrumental delivery (OR = 1.21, 95% CI 1.03-1.44), and oxytocin use (OR = 1.20, 95% CI 1.01-1.43) when compared with epidural on request plus nonpharmacological labor pain control methods such as one-to-one support, breathing techniques, and relaxation. Induction and acceleration of labor showed heterogeneous patterns of associations with cesarean delivery and instrumental delivery.

Conclusions: Complex patterns of associations between obstetric interventions and modes of delivery were illustrated in an empirical model. Intermittent auscultation and nonpharmacological labor pain control interventions, such as one-to-one support during labor, have the potential for substantially reducing cesarean deliveries.