The present study was carried from January 1, 1980 to December 31, 1984 at the Vila Lobato Medical Center (CMSCVL), which is a primary outpatient clinic for children and pregnant women. We carried out a longitudinal and retrospective study with 132 children divided into two groups according to duration of hospital stay in the postpartum period and to rooming-in or staying in the traditional maternity ward. Statistical analysis indicated that the only variable that differed among the two groups as related to breastfeeding was rooming-in or staying in the maternity in the postpartum period. Despite a trend of longer duration of breastfeeding in the rooming-in group, this difference was not statistically significant. It is important, however, to consider the importance of the role of the CMSCVL in supporting breastfeeding as a factor that may have influenced the homogeneous characteristic of the groups. The median time to weaning for the whole population and for the maternity ward group was eight months, whereas for the rooming-in group it was 10 months. We also identified the reasons for weaning in the study population, and the findings were similar to those in the literature.