Maternal and Newborn Outcomes Following Waterbirth: The Midwives Alliance of North America Statistics Project, 2004 to 2009 Cohort.

INTRODUCTION Data on the safety of waterbirth in the United States are lacking. METHODS We used data from the Midwives Alliance of North America Statistics Project, birth years 2004 to 2009. We compared outcomes of neonates born underwater waterbirth (n = 6534), neonates not born underwater nonwaterbirth (n = 10,290), and neonates whose mothers intended a waterbirth but did not have one intended waterbirth (n = 1573). Neonatal outcomes included a 5-minute Apgar score of less than 7, neonatal hospital transfer, and hospitalization or neonatal intensive care unit (NICU) admission in the first 6 weeks. Maternal outcomes included genital tract trauma, postpartum hospital transfer, and hospitalization or infection (uterine, endometrial, perineal) in the first 6 weeks. We used logistic regression for all analyses, controlling for primiparity. RESULTS Waterbirth neonates experienced fewer negative outcomes than nonwaterbirth neonates: the adjusted odds ratio (aOR) for hospital transfer was 0.46 (95% confidence interval [CI], 0.32-0.68; P < .001); the aOR for infant hospitalization in the first 6 weeks was 0.75 (95% CI, 0.63-0.88; P < .001); and the aOR for NICU admission was 0.59 (95% CI, 0.46-0.76; P < .001). By comparison, neonates in the intended waterbirth group experienced more negative outcomes than the nonwaterbirth group, although only 5-minute Apgar score was significant (aOR, 2.02; 95% CI, 1.40-2.93; P < 0001). For women, waterbirth (compared to nonwaterbirth) was associated with fewer postpartum transfers (aOR, 0.65; 95% CI, 0.50-0.84; P = .001) and hospitalizations in the first 6 weeks (aOR, 0.72; 95% CI, 0.59-0.87; P < 0.001) but with an increased odds of genital tract trauma (aOR, 1.11; 95% CI, 1.04-1.18; P = .002). Waterbirth was not associated with maternal infection. Women in the intended waterbirth group had increased odds for all maternal outcomes compared to women in the nonwaterbirth group, although only genital tract trauma was significant (aOR, 1.67; 95% CI, 1.49-1.87; P < .001). DISCUSSION Waterbirth confers no additional risk to neonates; however, waterbirth may be associated with increased risk of genital tract trauma for women.