[The pregnancy during adolescence as a risk factor for low birth weight, Brazil].

OBJECTIVE To identify the role of pregnancy during adolescence as a risk factor to low birth weight (LBW). METHODS A stratified sample of live births from the Information System of Live Births in the municipality of Rio de Janeiro, in the period 1996-98, was selected. The risk factors of LBW were analyzed for the two strata composed by the mother age, 15-19 and 20-24 years old. For the statistical analysis, odds ratios and correspondent confidence intervals were estimated. Logistic regression procedures were used. RESULTS The LBW was significantly greater among the adolescent mothers group than the 20-24 years one. Regarding prenatal care, adolescents had a lower number of appointments and a higher percentage of no attendance. More than 50% of the older mothers completed high school, but only 31.5% among the younger mothers had the same level of instruction. The percentage of premature live births in this group was significantly greater. Differences were observed by type of hospital (public or private) and there was a predominant use of public hospitals by the adolescents. The logistic regression analysis showed a significant effect of the mother age on LBW, even when controlled for other variables. CONCLUSIONS The results suggest that further investigation on the mechanisms that underlie the association between LBW and pregnancy during adolescence should be carried out, taking into consideration sociocultural factors such as poverty and social deprivation, as well as biological and nutritional factors during pregnancy.