[Gestational weight gain and macrosomia in a cohort of mothers and their children].
To identify co-variables potentially associated to infant macrosomia, including excessive gestational weight gain. A cohort was investigated consisting of 230 pairs of mothers and children, residents of the City of Rio de Janeiro. Fetal macrosomia, defined as a birth weight > or = 4,000 grams was treated as the dependent variable. Statistical analysis of the relation between macrosomia and co-variables involved stratified analysis and multivariate logistic regression, which estimates odds ratios (OR) and 95% confidence intervals (CI 95%). The incidence of excessive gestational weight gain was 29.1%, varying from 10% for women under 20 years to 63.6% for women who had given birth to children with macrosomia. Macrosomia incidence was 4.8% for the group as a whole, 10.4% for women with excessive gestational weight gain and 2.5% for women with normal gestational weight gain. Women with excessive gestational weight gain and > or = 20 years exhibited a chance of developing macrosomia that was 5.42 times greater (CI 95%: 1.11-26.34). Within the final multivariate logistic regression model, only excessive gestational weight gain (OR = 5.83, CI 95%: 1.51-22.48) remained associated to infant macrosomia. Considering that excessive gestational weight gain was the only predictor related to macrosomia, it is important that preventive programs that take account of this predictor be implemented, avoiding undesirable fetal outcomes. Future studies should include a wider variety of macrosomia predictors and additional birth outcomes.