Water birth refers to childbirth, usually human, that occurs in water. Proponents believe water birth results in a more relaxed, less painful experience that promotes a midwife-like model of care. Critics argue that the safety of water birth has not been scientifically proven and that a wide range of adverse neonatal outcomes have been documented including increased mother or child infections and the possibility of infant drowning. A 2009 Cochrane Review of water immersion in the first stages of labour found evidence of fewer epidurals and few adverse effects but insufficient information regarding giving birth in water. Parent, child and birthing organizations have produced statements both supporting and criticizing water birthing.
Water birth offers perineal support for a birthing mother, which decreases the risk of tearing and reduces the use of episiotomy. A Cochrane Review found that immersion during the first stage of childbirth reduces the use of epidurals, though it could not reach any other conclusions for other stages of labour or other outcomes and did not have enough information to make any conclusions on full water birth. It did not find evidence of increased adverse effects for immersion during the first stages of labour.
Risks and concerns 
Various authors have documented adverse neonatal outcomes including "unexplained deaths, drowning and near-drowning, asphyxiation, water intoxication hyponatremia causing seizures, water aspiration leading to respiratory distress syndrome and respiratory failure, pulmonary edema, snapped umbilical cords, hypoxic-ischemic encephalopathy, pneumonia, and other infections including Pseudomonas bacteremia".
The British Royal College of Obstetricians and Gynaecologists and the Royal College of Midwives issued a joint statement supporting water birth for healthy women with uncomplicated pregnancies but does not recommend it in cases of complications.
In a 2005 commentary, the Committee on Fetus and Newborn of the American Academy of Pediatrics (AAP) released an analysis of the scientific literature regarding underwater births. The Committee noted several positive studies for underwater birth, but went on to criticize them for lacking proper scientific controls, a significant number of infant deaths and diseases, and the general lack of information to support the use of water births. The paper concluded:
The safety and efficacy of underwater birth for the newborn has not been established. There is no convincing evidence of benefit to the neonate but some concern for serious harm. Therefore, underwater birth should be considered an experimental procedure that should not be performed except within the context of an appropriately designed RCT after informed parental consent.
The AAP received numerous letters in response to the statement, many claiming passionately that water birth had strong benefits and minimal risks for both parents and children and criticizing the AAP for failing to publish positive studies about the practice. In response, an author of the statement noted that the claims made were unsubstantiated and based purely on anecdotal evidence, with no randomized controlled trials that would allow an evidence-based assessment of the safety and benefits of water births. The author concluded by urging for proponents to support such a trial, so the question could be answered. The editor of the journal Pediatrics, where the commentary was published, noted that no such trials had ever been submitted to the journal, which had a policy against publishing articles that are not based on scientific evidence. The reply concluded that "I have not received any science-based commentaries from the groups that you cite in your letter. We cannot publish every letter, based on opinions only, that we receive."
- Cluett, E. R.; Burns, E. (2009). Immersion in water in labour and birth. In Cluett, Elizabeth R. "Cochrane Database of Systematic Reviews". Cochrane database of systematic reviews (Online) (2): CD000111. doi:10.1002/14651858.CD000111.pub3. PMID 19370552.
- Schroeter, K. (2004). "Water Births: A Naked Emperor". Pediatrics 114 (3): 855–858. doi:10.1542/peds.2004-0145. PMID 15342864.
- Garland, D (2000). Waterbirth: An Attitude to Care. Elsevier. ISBN 0750652020.
- "Immersion in water during labour and birth" (pdf). Royal College of Midwives/Royal College of Obstetricians and Gynaecologists. 2006. Retrieved 2012-08-29.
- Batton, D. G.; Blackmon, L. R.; Adamkin, D. H.; Bell, E. F.; Denson, S. E.; Engle, W. A.; Martin, G. I.; Stark, A. R. et al. (2005). "Underwater Births". Pediatrics 115 (5): 1413–1414. doi:10.1542/peds.2004-1738. PMID 15867054.
- Hess, S. (2005). "Strong Opinions Versus Science in Water-Birth Controversy". Pediatrics 116 (2): 522–523; author 523 523. doi:10.1542/peds.2005-1334. PMID 16061620.