Risk factors for the increasing caesarean section rate in Southeast Brazil: a comparison of two birth cohorts, 1978-1979 and 1994

Background Brazil has the highest caesarean section (CS) rate in the world (36.4% in 1996). Methods Risk factors for increasing CS rate were studied in two population- based cohorts of singleton live births in families residing in the municipa lity of Ribeirao Preto, State of Sao Paulo, Southeast Brazil. The first com prised births from June 1978 to May 1979 (6750 births-one-year survey) and the second births from May to August 1994 (2846 births-4-month survey). Mul tiple unconditional logistic regression modelling was used to control for c onfounding. Results The CS rate rose from 30.3% in 1978-1979 to 50.8% in 1994. In 1978- 1979, socio economic, reproductive and demographic variables, and health se rvice factors were associated with CS rate. In 1994, only reproductive, dem ographic and health service factors remained associated, e.g. hour of deliv ery (from 7 a.m. to 12 p.m.), attendance by the same physician for prenatal care and delivery, greater than or equal to 4 prenatal visits, maternal ag e greater than or equal to 30 years, 1-3 previous live births and birthweig ht 3500-3999 g. Conclusion Caesarean section in Brazil is widely performed for non-medical reasons in which physician convenience plays an important role. There is an urgent need for public health interventions ro reduce the CS rate in Brazi l, mainly directed towards cultural beliefs and physician behaviour.