Intrauterine-pressure studies in African nulliparae: delay, delivery and disproportion.

Uterine activity was measured in 43 African nulliparae who were in the active phase of spontaneous labour and in whom delay in cervical dilatation had occurred. Details of labour were recorded on a partogramme, on which an alert and an action line had been drawn, and which were 2 h apart. Delay was defined as a cervical dilatation rate of less than 1 cm/h. Uterine activity was measured with a fluid-filled intrauterine catheter, an external strain gauge and a pressure-curve integrator. The uterine activity levels which were observed in association with delay are considerably less than those associated with normal labour progress. The uterine activity levels that were associated with pitocin augmentation after the action line and which resulted in vaginal delivery have been analysed. They were similar to the levels observed in normal labour. The uterine activity levels which were associated with 'failure to progress in labour' beyond the action line have also been analysed. It is argued that a minimum uterine activity level of 1800 kPas/15 min is required to fully test the cephalopelvic relation.