The Risks of Space Travel on Female Fertility and Reproduction

Space travel has long captured our imaginations, with visions of exploring distant planets and expanding human civilization beyond Earth. However, the harsh environment of space poses many challenges and health risks for astronauts, especially for long-duration missions. A recent article published in Nature sheds light on a critical but often overlooked aspect – how space travel uniquely impacts the female reproductive system.

One of the biggest concerns is space radiation exposure. Outside of Earth’s protective atmosphere and magnetic field, astronauts are bombarded by galactic cosmic rays and solar energetic particles. This high-energy ionizing radiation can damage DNA in cells throughout the body. The female reproductive system is particularly sensitive, as radiation exposure can accelerate the depletion of a woman’s finite supply of ovarian follicles. This reduces fertility and may lead to earlier menopause onset.

Animal studies have shown that simulated space radiation destroys ovarian follicles, resulting in decreased ovarian reserve. While the limited data on female astronauts has not definitively proven earlier menopause, there are reports of menstrual cycle disruption during spaceflight. More research is needed to fully understand the long-term impacts.

Microgravity is another factor that may affect female reproductive health. The weightless environment of space causes a fluid shift in the body and disrupts normal biological processes. For example, studies in mice have found that microgravity impairs the growth and development of ovarian follicles and embryos. Whether similar effects occur in humans is still unknown.

Interestingly, many female astronauts take oral contraceptives to suppress their menstrual cycles during missions. While this provides a practical solution to menstruating in space, the long-term reproductive impacts of extended ovarian suppression in the space environment are not well studied.

NASA astronaut Christina Koch takes an out-of-this-world 'space-selfie'
NASA astronaut Christina Koch takes an out-of-this-world ‘space-selfie’ by NASA Johnson is licensed under CC-BY-NC-ND 2.0

As we look ahead to longer space missions, including travel to Mars, protecting astronaut health is paramount. More research focused on female biology in space is critically needed. This includes longitudinal studies tracking reproductive outcomes in female astronauts, as well as controlled experiments on Earth using space environment simulators.

This figure illustrates GnRH secretion, as well as the downstream effects of FSH and LH. It also shows the action of FSH and LH on gonads, and depicts the two-cell, two-gonadotropin model of estrogen synthesis.

Some potential solutions are already being explored, such as improved radiation shielding in spacecraft and the development of pharmacological countermeasures. Personalized risk assessment based on an astronaut’s age and baseline fertility may also help inform mission planning. Preserving ovarian tissue prior to spaceflight has even been proposed as a way for female astronauts to protect their fertility.

Ultimately, to make space travel safer for everyone, we must prioritize research on the unique health challenges faced by female astronauts. By shining a light on this understudied but important issue, the recent Nature article is a step in the right direction. Solving these challenges will not only protect the health and fertility of female astronauts, but will enable humanity to take the next giant leaps in space exploration.