First-time mothers are less likely to need pain relief during labour if they use a birthing pool, according to researchers.
First-time mothers may have harder labours
Just using the pool during the first stage of labour cuts the need for epidural injections, say the Southampton University team.
The finding, published on the British Medical Journal website, could mean that women could enjoy some of the benefits of a water birth without having to deliver the baby underwater.
Some experts remain concerned that actually giving birth in the water may increase the risks to the baby.
The Southampton researchers compared two groups of first-time mothers experiencing slow progress
The women in the first group were immersed in a birth pool during the first stage of labour - the others were not.
The study showed that of the 49 women in the water group, roughly half needed an epidural, compared with two-thirds of the 50 women in the other group.
The water labours were less likely to require medical intervention to aid contractions - and the women in the pools generally reported being more comfortable.
Despite not having intervention as often, labour was no longer in the water birth group as among those having normal labours.
Dr Elizabeth Cluett at the University's School of Nursing and Midwifery, who led the study, said that it gave the lie to a theory that the water-birth mothers would take longer to deliver in the absence of drugs to induce contractions.
She said: "We believed that first-time mothers tend to get very stressed, a factor which causes hormonal changes and slow progress in labour,"
"Our study shows that by putting these women in water, we can relax them and ease the pain. We hope that our results will provide women with an option whereby they can give birth without the need for obstetric intervention."
The findings of the study were welcomed by Mary Newburn, from that National Childbirth Trust.
She said: "For over a decade, women have been telling us that being able to use a birth pool during labour helps them to cope with contractions and feel safe and secure.
"This research now confirms that being immersed in warm water eases labour pain. This reduces the need for drugs, which cross the placenta and can make the baby more sleepy and breastfeeding more difficult.
"This new research emphasises the importance of making birth pools available in all NHS maternity units in sufficient numbers for all women who want to use water during labour."
"Given the cost - to the woman and the health service - of birth interventions that can be avoided when water is used during labour, it makes sense for every unit to offer this option."
However, not everyone is convinced that full water births are a good idea.
A recent study by New Zealand researchers described four incidents in which babies almost drowned in birthing pools.