Delivery outcomes after day and night onset of labour.

OBJECTIVE: To describe the outcome of night onset of labour as compared with the day onset of labour to investigate if labour that begins at night is more efficient.

DESIGN: Retrospective review of labour and delivery data.

SETTING: A large United Kingdom maternity service.

POPULATION: Over the period of 10 years, there were 30,022 deliveries, of which 19,842 were studied.

METHODS: A United Kingdom maternity department database was used to identify deliveries over a 10-year period, and the delivery outcomes were retrieved from these records. The 19,842 labours were divided into two categories: night onset (22.00-06.00 h) and day onset (10.00-18.00 h).

MAIN OUTCOME MEASURES: Rates of operative intervention, augmentation, epidural usage and labour duration.

RESULTS: A significant difference in delivery outcome was noted (P=0.004) with the night-onset labours having more normal deliveries (83.6% vs. 82.5%), fewer caesarean sections (8.7% vs. 10.1%), fewer labour augmentations with syntocinon (14.9% vs. 19.5%, P<0.001), fewer artificial rupture of membranes (14.1% vs. 15.6% P<0.001) and a significantly shorter mean first stage duration (4 h 58 min vs. 5 h 7 min, P<0.05). The proportion of women from each group who delivered between 09.00 and 17.00 h was 3660 (31.1%) in the night-onset group and 2414 (30%) in the day-onset group (χ2=1.3, P=NS) Conclusions: Labours that start at night appear to be more efficient than labours that start during the day.