Numbers of deaths related to intrapartum asphyxia and timing of birth in all Wales perinatal survey, 1993-5

OBJECTIVES: To investigate the relation between the timing of birth and the occurrence of death related to an intrapartum event. DESIGN: Analysis of 107,206 births to Welsh residents in 1993-5, including 608 cases of stillbirth and 407 of neonatal death identified in the all Wales perinatal survey, the cause of death classified with the clinicopathological system. SUBJECTS: 79 normally formed babies stillborn or who died in the neonatal period, birth weight > 1499 g, for whom cause of death was related to an intrapartum event. MAIN OUTCOME MEASURES: Relative risk of death due to an intrapartum event according to the hour, day, and month of birth. RESULTS: Mortality was higher in babies born between 9.00 pm and 8.59 am than in those born between 9.00 am and 8.59 pm; relative risk (95% confidence interval) 2.18 (1.37 to 3.47). July and August births also had a higher death rate than births in other months; relative risk 1.99 (1.23 to 3.23). Weekened births had a higher death rate but it was not significant. CONCLUSIONS: The excess of deaths at night and during months when annual leave is popular may indicate an overreliance on inexperienced staff at these times. Errors of judgement may also be related to physical and mental fatigue, demanding a more disciplined systematic approach at night. Mistakes may be ameliorated by increasing shiftwork, but shifts should be carefully designed to avoid undue disruption of circardian rhythms. In addition, greater supervision by senior staff may be required at night and during summer months.