Water births and the research required to assess the benefits versus the harms.

The questions that must be asked about any health-care intervention, including the use of immersion in the second stage of labour with birth into the water, are: is it useful?, does it do any harm? and do any benefits outweigh any harms? There is little subjective evidence (and no reliable, objective evidence) of any benefit to the mother or baby from water birth. There are reports of uncommon, yet significant, adverse outcomes for babies including deaths and significant morbidity directly attributed to water birth. There are also sound physiological mechanisms that can readily explain the significant adverse outcomes reported. It remains unknown whether any benefits from water birth outweigh any harms given the small number of underpowered studies available. An appropriately sized randomised controlled trial of good quality remains the only reliable way to assess both the efficacy and the safety of water births. Babies should not be born into water unless enrolled in such trials.