The interaction of the level of dietary carbohydrate and exercise intensity during pregnancy on fetal growth and development /

Since glucose is the principal substrate used during exercise and is also the main metabolic fuel for the developing embryo and fetus, exercising during pregnancy could induce a competition for fuel between fetus and exercising muscles, perturbing glucose homeostasis. To determine if exercise during pregnancy would predispose the fetus to increased risk, pregnant rats were randomly assigned to a low (4%), moderate (12%) or high (60%) carbohydrate diet, and either rested or exercised on a rodent treadmill at a moderate (15.5 m/min) or high (24.3 m/min) intensity from day 16-21 of gestation. When food intake was controlled for in the statistical model as a covariate, the level of maternal dietary carbohydrate significantly influenced maternal liver weight, heart glycogen, insulin, amniotic fluid glucose and lactate, but not maternal plasma glucose, liver or skeletal muscle glycogens. In contrast, a restricted level of maternal dietary carbohydrate, lowered fetal weight as well as fetal plasma glucose, insulin and liver glycogen. Exercise intensity significantly altered only maternal lactate levels. The results indicate that acute exercise during pregnancy can have detrimental effects on fetal development only if carbohydrate energy is restricted. Otherwise, adequate carbohydrate in the maternal diet appears to protect the fetus