High gestational weight gain does not improve birth weight in a cohort of African American adolescents

Background: Because pregnant African American women and teens are at risk of low birth weight, they are frequently counseled to strive for gestational weight gains at the upper limits of the Institute of Medicine's recommended ranges. Objective: The objective was to examine whether such weight gains improve birth outcomes in a cohort of disadvantaged African American adolescents of low (<19.8), average (≥19.8 to ≤26.0), or high (>26) prepregnancy body mass index (BMI; in kg/m²). Design: Data were extracted from the medical charts of 1120 African American adolescents who received prenatal care at an innercity maternity clinic between 1990 and 2000 and analyzed by using analysis of covariance and multivariate regression methods. Results: Data were available for 815 adolescents, 711 of whom delivered at term (≥37 wk). Fifty-eight percent (n = 409) of all term deliveries and 74% of the high-BMI adolescents (n = 126) had gains in the upper half of or above the recommended ranges. For all BMI groups, the most significant differences in birth outcomes were found in comparisons of teens who gained below the recommended ranges with those who gained in the lower half of the recommendation range. Further gains were not clearly beneficial, particularly for infants of high-BMI mothers. Conclusions: African American adolescents entering pregnancy underweight or at average weight should be counseled to gain within the recommended ranges, whereas overweight adolescents need support to avoid excessive gestational weight gain. Such advice would be prudent in light of the known associations between obesity and the increased likelihood of chronic diseases.