Here's something you've probably never considered, but totally makes sense: Getting your period in space could kind of suck.
Way back in 1983, Sally Ride, the first woman in space, was asked by reporters, "How will you deal with menstruation in space?" The answer is still being worked out, although NASA has gotten better at dealing with the issue since the '80s.
Menstruation was actually a major factor in women not making the journey into space. In 1964, Drs. Johnnie Betson Jr. and Robert Secrest wrote about the dangers of putting a menstruating woman (called "a temperamental psychophysiological human”) in space and in charge of "a complicated machine." This paper effectively shut down the Lovelace's Women in Space Program and kept women grounded for another 20 years.
In an astronaut class taught by Ride in 2010, she reportedly explained that periods are not that big of a deal. "I’m not totally sure who had the first period in space," Ride explained, "but they came back and said, 'Period in space, just like period on the ground. Don’t worry about it.'"
An analysis published in the journal npj Microgravity by space gynecologist Dr. Varsha Jain and space pharmacologist Virginia Wotring reports that there are a lot of logistics to consider. Many women in space take hormonal birth control and skip the placebo days to suppress menstruation. However, for longer journeys, that becomes more complex — how many pill packs can you bring for a three-year mission to Mars? When every ounce of weight counts, that's not an ideal solution.
Jain and Wotring conclude that hormonal IUDs and implants might be better options, as they can last up to five years. However, since the effects of zero gravity on IUDs haven't been studied, there's no way to know if it could potentially dislodge and create a health issue — and you can't just run to your gyno if you're on Mars.