Exercise during pregnancy and maternal and fetal plasma corticosterone and androstenedione in rats

Adrenocortical glucocorticoid and androgen secretion is stimulated by exercise. Excesses of these hormones in fetuses can cause abnormalities in development. We measured maternal and fetal plasma corticosterone and androstenedione concentrations in Sprague-Dawley rats immediately after maternal exercise in exercise-trained mothers and at rest in sedentary mothers. To do this, we developed a technique for fetal blood sampling and assessed its effect on maternal and fetal plasma corticosterone concentrations. Under halothane anesthesia, maternal blood was collected by cardiac puncture and fetal blood was collected from carotid and jugular vessels. Corticosterone was not affected by the blood collection procedure. Corticosterone was significantly higher in exercised mothers and their fetuses after 30 min of running than in sedentary mothers and their fetuses at rest. Androstenedione was significantly higher in exercised mothers after 30 min of running than in sedentary mothers at rest, but fetal androstenedione was not different between groups. We conclude that this maternal exercise protocol elevates plasma corticosterone but not androstenedione concentrations in fetal rats.