Which characteristics differentiates women of the same age who are sterilized from those who are not?

A sample survey of 236 tubal ligation women and 236 non-sterilized controls , of 30 through 49 years of age and living in the city of Campinas, SP, Bra zil, paired by age and place of residence was carried out, in order to eval uate if there are characteristics features that allow to differentiate wome n who chose to be sterilized from those who are not. There were no differen ces between groups on years of schooling, employment, religion, and knowled ge on contraception. Tubal ligated women were significantly more often ever married, had a significantly greater number of pregnancies and of living c hildren. The greatest difference was with reference to the age of first lif e birth: 36% of sterilized women and 21% of controls had their first baby b efore age 20. No difference in socioeconomic characteristics between steril ized and non-sterilized women were found.