Table 2 summarizes the effect of hypergravity on female reproduction. Hypergravity exposure of nonpregnant rats produced no differences in mating ability or gestation, but fewer pregnancies resulted. Hypergravity at moderate levels of 1.46 and 2.28 g disrupted the ovulatory cycle by inducing prolonged diestrus in rats, suggesting that the reduction in the number of pregnancies observed in centrifuged rats is due to changes in the ovulatory cycles. Pregnancy did not occur in mice chronically centrifuged at 3.5 g. Even centrifugation at relatively low speeds of 1.411.47 g resulted in an increased tendency to abort, especially during early pregnancy.
Serova observed that centrifugation of rat dams at 2 g during early pregnancy resulted in a 33% incidence of spontaneous abortion, whereas in rats centrifuged during midpregnancy there were no cases of spontaneous abortion. These findings and the results of spaceflight studies suggest that exposure to gravitational forces different from Earth’s 1 g may interfere with early pregnancy events such as implantation.
Increased mortality has been reported in neonatal rats exposed to hypergravity, even with intermittent exposure to centrifugation during the periparturition period.