Introduction: Despite a growing body of evidence for waterbirth safety, a myriad of political and cultural issues result in limited use in US hospitals compared to other developed nations. The purpose of this article is to critically analyze the evidence on maternal and neonatal outcomes of waterbirth to help inform evidence-based clinical practice in the United States. Methods: A literature search was performed using electronic databases CINAHL, Ovid MEDLINE, PubMed, EMBASE, and PsycINFO. Thirty-eight studies, including 2 randomized controlled trials and 36 observational studies, were reviewed. Studies were conducted in 11 countries, mostly outside the United States. More than 31,000 waterbirths were described. Results: Aggregate results suggest that waterbirth is associated with high levels of maternal satisfaction with pain relief and the experience of childbirth, and may increase the likelihood of an intact perineum. Waterbirth is associated with decreased incidence of episiotomy and severe perineal lacerations, and may contribute to reduced postpartum hemorrhage. Data indicate no difference in maternal or neonatal infection rates or nursery admissions after waterbirth. Neonatal mortality rates are low and similar after waterbirth and uncomplicated conventional birth. The calculated cord avulsion rate is 2.4 per 1000 waterbirths; it is unknown how this compares to conventional birth due to a lack of data that permits direct comparison. Discussion: The majority of waterbirth research to date is observational and descriptive; thus, reported outcomes do not demonstrate causal associations. However, existing evidence is reassuring. Case-controlled studies have included thousands of women who gave birth underwater without an apparent increase in maternal or neonatal morbidity or mortality. Potential risks associated with waterbirth for women and neonates appear minimal, and outcomes are comparable to those expected in any healthy childbearing population.