Prenatal weight gains related to the birth of healthy-sized infants to low-income women.

Prepregnancy weight status and weight gain during pregnancy are major independent variables associated with infant birth weight. This study quantitated the influence of weight gain on birth weight and identified rates and total amounts of weight gain related to the birth of healthy-sized infants to healthy low-income women who entered pregnancy underweight, at normal weight, overweight, or obese. Data used in the study were obtained from randomly sampled prenatal health records from Maternal and Infant Care (MIC) projects in Cleveland and Minneapolis. Subsamples of healthy mothers who delivered healthy-sized infants were identified from each sample, and rates and total amounts of weight gain by prepregnancy weight status group were calculated. There were 384 healthy mother and healthy-sized infant pairs in the Cleveland subsample and 75 such pairs in the Minneapolis sample. Multiple regression analysis revealed that the influence of prenatal weight gain and birth weight varied depending on prepregnancy weight status. Prenatal weight gains related to the birth of healthy-sized infants (newborns with birth weights of 3,000 to 4,500 gm) to healthy mothers in the Cleveland MIC sample averaged 33 lb for underweight, 32 lb for normal weight, 29 lb for overweight, and 19 lb for obese women. Except for obese women, rates and total amount of weight gain associated with the birth of healthy-sized infants were equivalent for the two samples.