The effect of maternal weight gain in pregnancy on birth weight.

The association between maternal weight gain during pregnancy and the infant's birth weight was studied in 14,121 term singleton births. The parturients were stratified into four body-mass categories, three age groups, four parity groups, and three levels of educational attainment. A separate multiple regression analysis was performed for each category to control for the confounding effect of gestational age, maternal social class, ethnicity, cigarette consumption, marital status, age, parity, education, and weight for height. A significant positive influence of prenatal weight gain on birth weight was found for all subgroups. The effect varied depending on maternal pre-pregnancy body mass, age, parity, and the level of formal education.