AN EMPIRIC EVALUATION OF THE INSTITUTE OF MEDICINES PREGNANCY WEIGHT-GAIN GUIDELINES BY RACE

Objective: To examine associations between pregnancy weight gain outsi de and within ranges recommended by the Institute of Medicine and birt h weight by both prepregnant body mass index (BMI) and race-ethnicity. Methods: Mean birth weight and incidence of term low birth weight (LB W, less than 2500 g) and high birth weight (more than 4500 g) were com pared across BMI-pregnancy weight gain-race-ethnicity strata. Subjects were 173,066 white, black, and Hispanic low-income pregnant women att ending prenatal nutrition programs between 1990 and 1993. Results: Amo ng low and average BMI women (all race-ethnicity groups), weight gain within Institute of Medicine ranges resulted in significant LEW reduct ions; further LEW reductions at gains beyond Institute of Medicine ran ges were offset by increasing high birth weight risk. Among women of h igh and obese BMI, LEW trends were less pronounced; thus, the benefit of gaining within the Institute of Medicine range was less apparent. A lthough blacks in every BMI-weight gain category had lower mean birth weights than white women, gaining in the upper end of the Institute of Medicine ranges did not provide a consistent LEW reduction for black women; adjusted LEW odds ratios and 95% confidence intervals for gains in the upper relative to the lower half of the Institute of Medicine range were 1.3 (0.8, 2.1), 0.7 (0.5, 1.03), 0.3 (0.2, 0.8), and 1.3 (0 .7, 2.5) for black women of low, average, high, and obese BMI, respect ively. Conclusion: Institute of Medicine pregnancy weight gain ranges recommended for low and average BMI women appear reasonable, but recom mendations for high and obese BMI women require further evaluation. Th e recommendation that black women in all BMI groups strive for gains t oward the upper ends of the ranges is not supported clearly by these d ata.