Effects of food restriction on fetal and placental growth and maternal body composition.

The effects of food restriction on net body weight and composition were studied in pregnant and non-pregnant rats. Control pregnant rats gained 81.7 g during the observation period. On day 21 of gestation their carcasses contained 17 per cent fat, 23 per cent lean dry mass and 60 per cent water. During a similar period non-pregnant controls gained 31.5 g and their carcasses contained 13 per cent fat, 24 per cent lean dry mass and 63 per cent water. Pregnant animals fed daily 50 per cent of the quantity consumed by pregnant controls lost 5.9 g and at day 21 of pregnancy their carcasses contained 9 per cent fat, 25 per cent lean dry mass and 66 per cent water. Non-pregnant rats pair-fed with the pregnant restricted group lost 13.7 g of body weight. Their carcass composition was virtually identical to the pregnant restricted group. Both fetal and placental weights were reduced by food restriction. The results indicate that restricted pregnant rats, while failing to gain as well as the control group, were able to maintain their body weight and composition as well as the non-pregnant restricted animals. The data suggest that during undernutrition the mother does not mobilize pre-pregnancy nutrient stores to sustain fetal growth.