Experts analysed 397 water births and 2,025 bed births. The results were published in the journal Birth.
Results showed there were no differences in rates of babies admitted to intensive cares or postpartum haemorrhage, when the mother bleeds heavily after birth.
It is difficult to measure how much blood has been lost in water. Therefore, pregnant women at high risk of bleeding are unlikely to be offered such births.
Women in the water group sustained fewer tears, which may be because the water helps with stretching of their vagina.
Dr Ruth Zielinski, study co-author, argued more facilities should offer water birth and have guidelines for implementing it.
Few US hospitals or birth centers offer water births because of perceived risk to the newborn.
Guidelines released by the American Academy of Paediatrics and American College of Obstetricians and Gynaecologists said in 2014 that women should not routinely be offered an underwater delivery.
The organisations said: ‘A woman who requests to give birth while submerged in water should be informed that the maternal and perinatal benefits and risks of this choice have not been studied sufficiently.’
However, in the UK, a water birth is an option for any woman with a low-risk pregnancy.
The Royal College of Obstetricians and Gynaecologists and Royal College of Midwives say the evidence to support water births is not clear, but complications are rare.
There are certain guidelines that must be followed, such as rigorous cleaning of the tubs to ensure low-risk of infection.
The water temperature should be around body temperature to avoid the mother or baby getting too hot or cold, it is advised.
Professor Zielinski said it’s important not to re-submerge babies once they have been slowly lifted from the water because their lungs could fill with water.
When they are brought to the surface, they take their first breathe of air. Before that point, while still underwater, their oxygen supply comes from the mother through the umbilical cord.
Birthing pool are useful for women who feel anxious about birth because the water is relaxing. Around two in ten women in England use it during labour for this or to feel more comfortable during contractions.
There are some drawbacks – for example you cannot have some types of pain relief during a water birth such as an epidural.
Professor Zielinski said more studies are needed to understand the satisfaction level of women who have water births.
But Lisa Kane Low, senior author of the Michigan paper, said: ‘The long and short of it is that if you use proper techniques… the outcomes [of water births] are very good.’