Factors associated with rapid labour in nulliparae.

The objective of this study was to assess the factors which may influence rapid labour in nulliparae. This is a cohort study of 991 consecutive nulliparae who were admitted in spontaneous labour with a singleton pregnancy and cephalic presentation. The setting was the National Maternity Hospital, Dublin where active management of labour is applied to all nulliparae fitting the above criteria. Rapid labour of 2 hours or less occurred in 82 patients (8.3%). Dilatation of 2 cm of the cervix on admission in labour, gestation of less than 37 weeks, and diminishing birthweight, were more common in rapid labours compared with other labours. Women in rapid labour were not surprisingly less likely to require oxytocin augmentation, or to need operative vaginal delivery or Caesarean section, receive epidural anaesthesia, or attend antenatal classes, compared with other women in labour. Rapid labour was not influenced by the finding that the membranes were already ruptured before admission, the time spent at home with contractions, or social background. Women with rapid labour were more likely to arrive in hospital within 4 hours compared with other women in labour. Rapid labour depends on the efficiency of uterine action which is reflected by the dilatation of the cervix on admission.