Caesarian sections in Guadalajara, Mexico: sociodemographic risk factors.

on the population covered by the Mexican Social Security Institute (MSSI). The MSSI offers health services to people with a steady job (for example, industrial and services workers, employees, teachers) and their families and attends about 60% of childbearing in Guadalajara. A probabilistic sample was designed, representative of the first live births (25 662) and their respective mothers. Subjects were randomly chosen from the MSSI 1992-93 birth registers. The original sample size was 545, but because some dwellings were not found, data