[Frequency and determinants of breastfeeding in the State of São Paulo, Brazil].

OBJECTIVE To meet the information need of Brazilian municipalities concerning breastfeeding practices as part of health care planning, a study was carried out to describe breastfeeding and to identify weaning-related factors. METHODS Of all municipalities in the State of São Paulo, Brazil, openly called to participate in the study, 84 joined in. Personnel underwent training to collect data during the national mass immunization day in 1998. A sample strategy, proportional to the infant population, was developed for each participant. Standardized questionnaires were applied to assess infant feeding practices in the previous 24 hours. Descriptive statistic analysis on breastfeeding prevalence and logistic regression analysis of risk factors for discontinuing exclusive breastfeeding of infants aged less than 4 months and weaning of infants aged less than a year were performed. RESULTS Exclusive breastfeeding rates in the first four months of life were under 30%. The risk factors were: lower maternal education status; lack of access to the so-called "Baby Friendly Hospital Initiative"; primiparity; and early age pregnancy. Around 50% of children under a year old were breastfed. CONCLUSIONS Lacks of access to the "Baby Friendly Hospital Initiative", primiparity, and mother's unemployment or engagement in an informal occupation activity were risk factors for weaning. Local breastfeeding rates are extremely variable in the State of São Paulo, reinforcing the importance of local, swift, and easily feasible health care actions.