Research on Sex and Gender Health Differences Reaches New Levels

It was 1969 when man--literally--first landed on the moon. I was only about 6 then, but it was an unforgettable event. Several years later, when talking to my mother about careers, I mentioned that I was considering becoming an astronaut. She hesitated and said, “That would be unlikely, because only men go to the moon.”

Things have changed. Of the 534 people to travel into space, 57 (11%) were women.

To ensure the health and safety of all astronauts, NASA and other federal agencies analyzed International Space Station data to fully understand sex and gender differences in space. The Journal of Women’s Health recently published six research papers highlighting the effect of sex and gender on adaptation to space travel. Although the conclusions of these studies may be limited because so few women have travelled into space, it is not surprising to find that men and women adapt differently to the stress of space travel.

In space:

• Male astronauts suffer more from vision and hearing impairment.
• Female astronauts experience more motion sickness during the transition to microgravity.
• Female astronauts have a higher prevalence of urinary tract infections (which are treatable with antibiotics).

Upon return to Earth:

• Women have more difficulty standing without fainting for prolonged periods.
• Men experience more motion sickness.

Space travel affected women and men about the same in relation to bone and muscle loss--a serious condition associated with microgravity--and behavioral and psychological responses. Space exploration has no observable effect on female fertility (13 women astronauts gave birth to 18 children following their space travels); there has been no follow-up on the health of these children.

One of the most serious differences in health risks related to space exploration is sensitivity to radiation exposure. Women have a higher incidence of radiation-induced cancers (e.g. lung and breast cancer), as well as a 50% higher cancer mortality rate than men. So what contributes to these differences observed among female and male astronauts? Among those being studied include sex differences in hormones, metabolism, body structure/components, stress responses and immune responses.

Understanding sex and gender differences to adaptation to space flight is absolutely critical as more women join space training programs. Let’s hope these studies will shed light on sex- and gender-based differences in health and disease for those of us staying on Earth!

This post was written by Christine Metz, PhD.

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