How spaceflight affected the next generations of female mice

Female mice that returned after 42 days on the International Space Station were able to produce healthy offspring upon returning to Earth, but significant reproductive changes were identified in their daughters and granddaughters. The study, published in the journal Proceedings of the National Academy of Sciences, is the first scientific work to examine the long-term effects of spaceflight on female reproductive physiology over several generations. This scientific project was carried out by specialists from the University of Kansas Medical Center and scientists from NASA's Ames Research Center. This is reported by Ixbt.com reports .

According to ixbt.com, the female rodents participating in the experiment were sent to the ISS in November 2023 via the SpaceX CRS-29 cargo spacecraft. The mother mice, who spent 42 days off-Earth, became pregnant successfully and gave birth to healthy pups. Although the number of their offspring was slightly lower than that of the control group, the difference was not statistically significant, and the first-generation representatives developed normally.

Changes observed in the second generation

However, experts noted that the main changes and negative effects became clearly apparent in the subsequent generations of the space travelers. It was found that the daughters of the mothers who had been in space had 15 percent lower muscle strength. They also exhibited high levels of stress response in specific behavioral tests, and most importantly, their own fertility rates dropped significantly, leading to fewer offspring.

In these same female mice, a decrease in the level of the anti-Müllerian hormone (AMH), an important marker indicating the remaining ovarian reserve, was recorded. Interestingly, the reduced AMH levels persisted even in the third-generation granddaughters. Scientists stated that they have not yet fully established the exact mechanism of this transgenerational effect and that further research is ongoing.

Potential causes and future risks

According to the experts' working hypothesis, this condition may be related to accelerated cellular aging caused by microgravity. Previous studies have also observed cellular stress and mitochondrial dysfunction in human tissues and rodents under weightless conditions. Considering that mitochondrial DNA is transmitted only through the maternal line, this could theoretically explain the transgenerational effect, but this version still requires direct experimental verification.

At the same time, the authors drew attention to some limitations of the study. Specifically, the sample size in the experiment was not very large—only 20 female mice that had flown were observed, and the flight lasted 42 days. Furthermore, since the ISS is located within the protection of Earth's strong magnetic field, the crew and animals receive significantly less cosmic radiation than they would on a trajectory to the Moon or Mars. Ulrike Luderer from the University of California noted that her work on radiation doses for Mars missions showed a sharp decline in ovarian reserves, serving as an important warning that reproductive markers must be strictly monitored in future long-term space programs.