Births and perinatal deaths in Australia: variations by day of week.

Analysis of births occurring in Australia during 1976-9 showed that they followed a seven-day cycle, being concentrated on Tuesdays to Fridays and least numerous on Sundays, which had 26% fewer births than expected. Stillbirth and neonatal death rates were 17% and 29% higher respectively among babies born at weekends than among those born on weekdays. The incidence of low birth weight was also significantly higher in the weekend group in New South Wales. The patterns seen in births and perinatal deaths are largely associated with the selective effects of intervention in delivery rather than with any variation in quality of care throughout the week.