Maternity units will come under pressure to offer more women birthing pools during labour after research suggested immersion in water cut the need for epidural anaesthetics.

A study by a team at Southampton general hospital reported that first-time mothers-to-be undergoing slow labour were also less likely to need drugs to increase contractions. The women said they suffered less pain and were more satisfied with their freedom of movement than those having more standard treatment. But numbers undergoing Caesarean or assisted delivery with forceps or suction equipment for the delivery were similar.

The results, reported today on the medical journal BMJ Online, involved only around 100 women but they were welcomed by the National Childbirth Trust whose poll of members last year suggested many women were not being offered pools during labour or birth.

Mary Newburn, the trust's head of policy research, said women felt pools helped them cope with contractions and feel safe. "Given the cost, to the women and the health service, of birth interventions that can be avoided when water is used, it makes sense for every unit to offer this option."

The Southampton researchers found about half the 49 women in the water group needed an epidural, compared with two-thirds of the 50 women having standard treatment. A fifth of the women in the water group needed no more obstetric interventions.

Studies have suggested women undergoing normal labour report increased satisfaction from immersion. But the idea that those undergoing longer labour also benefit encourages campaigners.

The research team says more study is needed of the medical outcomes for babies born after their mothers used pools.