How does the presence of midwives affect care and birth outcomes?

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Although the proportion of hospital births attended by midwives has been steadily increasing, the impact of their presence on labor care and perinatal outcomes remains unclear. A recent study, published in Birth, compared labor care processes and birth outcomes between healthy, low-risk nulliparous women birthing in United States medical centers with interprofessional (midwives and physicians) versus non-interprofessional (only physicians) care.

Using data from the Consortium on Safe Labor (CSL), the authors were able to collect data (demographics, medical history, reproductive and prenatal history, labor interventions, birth outcomes, postpartum and discharge information, and newborn information) from women’s health records acquired from 12 clinical centers between 2002 and 2008. Two variables in the database specifically indicated whether women labored and birthed at an interprofessional medical center or non-interprofessional center. Only healthy nulliparous women who gave birth to a single, cephalic-presenting fetus at or after 37.0 weeks’ gestation were included in the study.

The main labor care processes and birth outcomes measures used for analysis included gestational age of newborn at birth, type of labor onset, rupture of membrane type, oxytocin augmentation use, mode of birth, maternal postpartum blood transfusion, maternal postpartum intensive care unit admission, neonatal intensive care unit admission, and adverse neonatal outcomes.

The final sample included 14,375 women, with 7,393 birthing at an interprofessional medical center and 6,982 giving birth at a non-interprofessional center. Among the interprofessional centers, physicians attended all births, though midwives were present at approximately 18% of these births. Women birthing at interprofessional centers were younger and more likely to be white and/or have private insurance. Birth interventions such as induction of labor, amniotomy, oxytocin augmentation and cesarean birth were used less often at interprofessional centers (P < 0.001 for each). Duration of in-hospital time from admission to birth was 2.7 hours shorter for women birthing at interprofessional medical centers and postpartum blood transfusions were administered less often.

Adjusted models indicated that women at interprofessional centers were 27% less likely to birth at early term (P < 0.001) but more likely to birth at late-term or post-term compared to women at non-interprofessional centers.

Propensity-adjusted models also indicated there was a 74% lower risk of labor induction at interprofessional centers (RR 0.26, 95% CI 0.24-0.28) and a 63% lower risk of a cesarean birth before a trial of labor (RR 0.37, 95 % CI 0.30-0.47). Oxytocin augmentation was used less frequently (RR 026, 95% CI 0.24-0.29) and amniotomy use was 17% less likely (P < 0.001) at interprofessional centers as well.

The authors believe their findings indicate that the care processes and birth outcomes differ significantly between interprofessional and non-interprofessional medical centers. They believe their findings may reflect the influence of core aspects of midwifery philosophy of care, including watchful waiting and nonintervention in normal processes. They suggested that the presence of midwives resulted in fewer interventions during labor and a greater likelihood for vaginal births among low-risk nulliparous women.