[The prevalence of exclusive breastfeeding and associated factors: a cross-sectional study of teenage mothers between 14 and 16 years of age in the city of Porto Alegre in the State of Rio Grande do Sul, Brazil].

This is a cross-sectional study to verify the prevalence and associated factors related to exclusive breastfeeding in adolescent mothers between 14 and 16 years of age with 6-month-old or younger babies, born in Porto Alegre in the State of Rio Grande do Sul, Brazil, in 2009. The sample was based on 50% of the newborn babies from the population surveyed. A total of 341 adolescent mothers were interviewed in their homes. The variables considered as potential determinants of exclusive breastfeeding were social and demographic, pre- and post-natal assistance, emotional aspects of the mother, birth conditions and baby characteristics. Prevalence ratios (PR) were estimated by Poisson regression by means of hierarchical analysis. The prevalence of exclusive breastfeeding ranged from 47.8% in the first month of life up to 13.8% after six months and declined, on average, 24% for each month of life (RP = 0.76; CI95%: 0.68-0.85). Besides the baby's age, the factors associated with exclusive breastfeeding were maternal education (PR=1.53; CII95%: 1.18-1.98) and multiple births (PR=1.57; CI95%:1.02-2.46), the latter observed in only 4.7% of the sample. Teenage mothers with higher schooling and with live children from earlier pregnancies manifested higher prevalence of exclusive breastfeeding.