 We hypothesize that women with lower resting metabolic rates RMR in the first trimester will demonstrate a greater maternal weight gain, when adjusted for caloric intake and activity. It is also hypothesized that for a given RMR, the degree of maternal insulin resistance IR predicts birthweight adjusted for a given caloric intake. A third hypothesis is that women with increased insulin resistance measured by HOMA will result in neonates with larger birth weights and a greater degree of neonatal fat mass as measure by DEXA scan, adjusted for RMR and diet characteristics. 