Brazil has one of the highest rates of cesarean births, and the number has been growing annually. The scope of this study was to test the possible consequences arising from this increase on the date of birth. The 1,933,137 live births that occurred in São Paulo, Brazil, from 2001 to 2010 were analyzed by type of delivery and exact date of birth. In 2001, 48.9% of all births were by cesarean section, increasing to 56.8% in 2010. During th is period, the difference between the number of births occurring on Sundays (the day of the week with the lowest number) increased from 111.4 (95%CI: 101.7 - 121.0) in 2001, to 143.1 (95%CI: 135.0 - 151.3) in 2010. The two dates with the lowest number of births (Christmas day and the Day of the Dead), had a statistically significant (p < 0.05) difference from the other days of the year during most of the period (the exception being the Day of the Dead in 2009). The date with the highest number of births (International Women's Day) showed a statistically significant d ifference in 2005 and 2010. The increase in the number of cesarean births has had a significant impact on date of birth, which could have consequences for the administrative planning of health institutions.
Live births; Cesarean sections; Health institutions; Date of birth
