First-time mothers making slow progress with labour reported "significantly" less pain when immersed in water, according to a new study.
They less often needed drugs to overcome pain and needed fewer medical interventions to deliver their babies.
Dr Elizabeth Cluett of the University of Southampton and colleagues studied women experiencing slow labour.
They compared labouring in water with standard drug-based measures to boost the progress of labour, publishing their findings yesterday in the British Medical Journal.
"Slower than expected progress in the first stage of labour (dystocia) occurs in 20 per cent of [First time\] women in labour and accounts for 20 per cent of caesarean sections and 40 per cent of instrumental deliveries and results in longer hospitalisation," the authors write.
The trial was based on two assumptions, that a lack of understanding of labour could lead quickly to unnecessary medical intervention, and that anxiety and pain triggered stress, slowing the progress of labour still further.
"Labouring in water may ameliorate this stress response by aiding relaxation and pain relief," the authors suggested, prompting the two-year analysis that concluded in December 2000.
The study included 99 women experiencing slow labour, defined as cervical dilation of less than one centimetre per hour. Half of them were immersed in a birth pool during the first stage of labour, while the rest received standard care including the use of oxytocin to speed up contractions.
The study showed that the 49 women in the water group were less likely to need drugs to aid contractions and reported significantly lower pain scores. It also showed that only about half of these women needed complete pain relief using an epidural, compared with the two-thirds needing an epidural among the 50 women in the standard care group.
The average duration of labour in both groups was about the same as was the number of caesarean sections and forceps deliveries.
Before this trial the assumption was that all women with slow labour would require labour "augmentation" using oxytocin or having their waters broken, and that they would have longer labour and frequently needed obstetric intervention, the authors report.
"However almost 30 per cent of women in the water arm did not receive augmentation and 20 per cent received no obstetric intervention, without evidence of longer labour, both of these rates being significantly different from the augmentation arm."
They retrospectively reported less pain and increased satisfaction with greater freedom of movement, the authors add. "Also a management approach that reduces rates of augmentation and associated obstetric intervention may contribute positively to maternal physiological and psychological health: oxytocin infusion is known to increase the risk of uterine hyperstimulation and fetal hypoxia [lack of oxygen], and obstetric interventions are associated with lower maternal satisfaction."