Increasing access to certified nurse-midwives prevents use of medical interventions during labor: an application of g-computation and target trial emulation

BackgroundPrenatal care (PNC) led by a certified nurse-midwife (CNM) may reduce medical interventions and complications during labor and delivery, compared to physician-led care. We estimated the prevalence of six outcomes if we intervened to increase the number of low-risk pregnant people enrolled in PNC with a CNM. MethodsWe used 2014-2019 Pregnancy to Early Life Longitudinal data. The study population comprised people aged 18-55 with a low-risk pregnancy who initiated PNC with a physician or CNM at <13 weeks gestation and had a live birth. We used g-computation to estimate the prevalence and prevalence difference of cesarean sections, labor inductions, epidural use, postpartum hemorrhage, maternal infection and obstetric trauma under hypothetical scenarios where 10%, 20% and 50% more people and 100% more people with government-funded insurance had CNM-led PNC. We adjusted for payer of delivery, maternal age, education, race, and estimated 95% confidence intervals (CI) using bootstrap resampling. ResultsAmong 130,835 pregnant people, one-fourth had CNM-led PNC. A 10% increase in CNM-led PNC resulted in a reduction in the prevalence of cesarean sections of -0.39 percentage-points (95% CI: 0.41 to -0.35), in labor inductions of -0.21 percentage-points (95% CI: -0.25 to -0.17), in epidural use of -0.85 percentage-points (95% CI: -0.89 to -0.80), and in maternal infections of-0.08 percentage-points (95% CI: -0.11 to -0.06), but an increase in prevalence of postpartum hemorrhage of 0.03 percentage-points (95% CI: 0.01 to 0.05) and no change in prevalence of obstetric trauma (0.00 percentage-points; 95% CI: -0.02 to 0.03). The effect estimates were larger for 20% and 50% increases. ConclusionsA scale-up of CNM-led care contributes to a decrease in use of some medical interventions and complications during labor and delivery. Key PointsOur results suggest that interventions to increase the number of low-risk pregnancies attended by CNMs versus physicians could reduce the use of some medical interventions and complications during labor and delivery. With 10% more low-risk pregnant individuals enrolled in prenatal care with a CNM, the prevalence of cesarean sections, labor inductions, epidural analgesia, and maternal infection decreased, while the prevalence of postpartum hemorrhage increased slightly, and the prevalence of obstetric trauma did not change. As barriers to accessing care with a CNM still exist for low-risk pregnant populations, policy makers and clinical providers should help to reduce barriers to access to CNMs to help improve clinical outcomes.