Mouse study hints space travel could reduce fertility in later generations

Female mice that spent 42 days aboard the International Space Station showed normal fertility, but their offspring and grandchildren had smaller litters, fewer litters, and lower reproductive hormone levels. The findings, published in PNAS, suggest spaceflight may have transgenerational effects on reproduction, though the relevance to human astronauts remains uncertain. Researchers emphasize the need for further study as long-duration space missions become more common.

The research involved female mice that spent 42 days aboard the International Space Station, having traveled there on NASA's SpaceX CRS-29 mission. Published June 30 in PNAS, the study found that while the space-exposed mice themselves showed normal fertility, their children and grandchildren experienced measurable reproductive declines, including smaller litters, fewer total litters, and reduced levels of key reproductive hormones. Study co-author Lane Christenson noted that offspring showed alterations across behavior, muscle function, and reproductive capacity.

This work addresses a gap in spaceflight research, which has largely focused on male subjects. A 2019 study found male mice could father healthy offspring after ISS exposure, while the NASA Twins Study examined short-term effects on human astronauts. The new findings underscore how estrogen influences nearly all organ systems in females, making reproductive health a critical consideration for long-duration missions.