ABSTRACT
The effects of daily maternal exercise on fetal-placental growth and development and the associated changes in uteroplacental blood flow were studied in pregnant rats. Pregnant females were exercised for 1 h (0% grade at 28 m/min) daily between either days 1 and 12, 1 and 18, 1 and 22, 12 and 18, or 12 and 22 of gestation and compared with nonexercised controls. Exercise between days 1 and 12 of pregnancy had no effect on fetal-placental parameters (i.e., fetal weight or gestation length) relative to controls. In contrast, exercise between days 1 and 22 and 12 and 22 resulted in a lower number of live pups born, an increase in gestational length, and an increased birth weight of the live pups relative to controls. Exercise between days 1 and 18 or 12 and 18 induced a significant (p less than or equal to 0.05) suppression of uteroplacental blood flow, the number of viable fetuses, and placental weights as compared with controls. Daily exercise had no effect on ovarian function as indicated by the comparable serum progesterone levels in all groups. These data indicate that an exercised-induced depression of uteroplacental blood flow is related to impaired fetal-placental growth and development during pregnancy in the rat.