Effect of maternal dietary restriction during pregnancy on maternal weight gain and fetal birth weight in the rat.

The effects of the following dietary regimes on maternal body weight and weights of the products of conception were investigated in the laboratory rat: 50% dietary restriction during the catabolic phase (days 15--21) of gestation; 50% dietary restriction during the anabolic phase (days 1--14) but adequate nutrition during the catabolic phase, and 50% dietary restriction throughout gestation. Total body weight and net maternal weight at term were significantly reduced in all three test groups. Restricting dietary intake during the anabolic phase resulted in decreased maternal weight gain. Feeding an adequate diet during the catabolic phase, following restriction during the anabolic phase, caused only a slight decrease in net maternal weight, while term fetal weight approximated that of controls. Dietary restriction during the catabolic phase, or throughout gestation, caused increased net maternal weight loss. Term fetal weight in both groups was significantly lower than that of the controls, but not different from each other. The results indicate that the dam is able to mobilize nutrients stored during the anabolic phase of pregnancy. Mobilization of these nutrients did not significantly increase fetal growth, however, supporting the hypothesis that the dam is able to compartmentalize available nutrients during malnutrition and prevent serious depletion of these stores by the fetus.