Communication of pain: vocalization as an indicator of the stage of labour.

The sounds made by women in the first and second stages of labour were recorded. One minute segments were replayed to 40 medical staff with at least 6 months labour ward experience who were asked to determine whether the sounds played were made by a woman in the first or second stage of labour. The stage of labour associated with each of the sound segments was correctly identified at much greater than chance frequency. It is suggested that further research into the nature and significance of these sounds may have the potential to allow them to be used more systematically by midwifery staff as an unobtrusive aid in monitoring the labour process.