Prenatal weight gain within upper and lower recommended ranges: effect on birth weight of black and white infants.

OBJECTIVE: To that end examine differences in birth weight among the term infants of black and white women with weight gains in the upper or lower half of recommended ranges.
METHODS: Birth weight (mean, low [at or below 2500 gl, and suboptimal [2501-2999 g]) among term infants of 2219 black and 3966 white low-income women was compared with maternal prenatal weight gain classified according to four categories: below, within the lower or upper halves, and above the recommended ranges for pregravid body mass index (BMI) category (low, normal, high).
RESULTS: Adjusted mean birth weights among the infants of women with prenatal weight gain in the upper versus lower half of the recommended ranges were higher among white women with normal BMI (3307 g upper half, 3199 g lower half, P = .001) but not among black women with normal BMI (3180 g upper half, 3105 g lower half, not significant). Logistic regression analyses revealed that prenatal weight gain in the upper compared with the lower half of the recommended ranges was associated with a decreased adjusted odds ratio (OR) for low (but not suboptimal) birth weight among the infants of white women (OR 0.4, 95% confidence intervals [CI] 0.2,0.9) but not of black women (OR 1.2; 95% CI 0.4,3.3).
CONCLUSION: These preliminary observations do not provide support for the presence of ethnic group-specific recommendations within guidelines for prenatal weight gain.