Birth Setting Related Outcomes Among Low-Risk, Midwife-Attended Births in Washington State

Community births attended by midwives have gained attention for their potential to support physiologic childbirth and reduce medical interventions compared to hospital births. However, outcomes comparing midwife-attended births following low-risk pregnancies in community and hospital settings remain understudied. Among midwife-attended births, we examined overall and parity-specific associations of birth setting with physiologic birth and hospital admission within 30 days of delivery for birthing parents and infants. Methods: This retrospective cohort study analyzed data from the Obstetrical Care Outcomes Assessment Program (OB COAP) in Washington State. The study included 1,442 low-risk midwife-attended births between January 2022 and March 2023. Planned birth settings were categorized as community (home or birth center) or hospital. Physiologic childbirth (defined as spontaneous labor and birth without medical interventions) and hospital admissions within 30 days post-delivery for birthing parents or newborns were the primary outcomes. We used crude and adjusted (for birthing parent age, geographic residence, race, ethnicity, insurance payor type, parity, gestational age, and pre-pregnancy body mass index) modified Poisson regression models to estimate relative risks (RRs) and corresponding 95% confidence intervals (CIs). We also evaluated parity as a potential effect modifier of the associations using stratified analyses and models with interaction terms.