http://www.sciencedaily.com/releases/2016/01/160121190918.htm
There is no evidence that water births, where a baby is intentionally born under water in a tub or pool, poses any increased harm to the child, Oregon State University researchers have found.
Researchers examined outcome data for more than 6,500 midwife-attended water births in the United States and found that newborns born in water were no more likely to experience low Apgar scores, require transfer to the hospital after birth or be hospitalized in their first six weeks of life, than newborns who were not born in water.
(click link to read the entire study on sciencedaily.com)