A prospective cohort study of the morbidity associated with operative vaginal deliveries performed by day and at night

Objective: To evaluate maternal and neonatal outcomes associated with operative vaginal deliveries (OVDs) performed by day and at night. Design: Prospective cohort study. Setting: Urban maternity unit in Ireland with off-site consultant staff at night. Population: All nulliparous women requiring an OVD with a term singleton fetus in a cephalic presentation from February to November 2013. Methods: Delivery outcomes were compared for women who delivered by day (08:00-19:59) or at night (20:00-07:59). Main outcome measures: The main outcomes included postpartum haemorrhage (PPH), anal sphincter tear and neonatal unit admission. Procedural factors included operator grade, sequential use of instruments and caesarean section. Results: Of the 597 women who required an OVD, 296 (50%) delivered at night. Choice of instrument, place of delivery, sequential use of instruments and caesarean section did not differ significantly in relation to time of birth. Mid-grade operators performed less OVDs by day than at night, OR 0.60 (95% CI 0.43 to 0.83), and a consultant supervisor was more frequently present by day, OR 2.26 (95% CI 1.05 to 4.83). Shoulder dystocia occurred more commonly by day, OR 2.57 (95% CI 1.05 to 6.28). The incidence of PPH, anal sphincter tears, neonatal unit admission, fetal acidosis and neonatal trauma was similar by day and at night. The mean decision to delivery intervals were 12.0 and 12.6 min, respectively. Conclusions: There was no evidence of an association between time of OVD and adverse perinatal outcomes despite off-site consultant obstetric support at night.