Space Menstruation Deserves Further Study

Most female astronauts decide to not get their period while in space. Eric Meola/Dorling Kindersley/Getty

Menstruation in space! 

Yes, snicker, cringe or throw something at the author, but space menses are a real concern for human space travel. After all, half the human race experiences this regular discharge of blood and tissue. And while females historically only make up 11 percent of human spaceflights thus far, NASA's latest class of astronauts is refreshingly 50/50 in the gender department.

But here's the thing: Just like every other bodily function, menstruation presents challenges for the already-momentous task of sending fragile humans beyond the confines of their terrestrial environment. Most female astronauts choose to avoid the challenges of orbital menses altogether, through either timing or menstrual suppression, but how's an XX-chromosome space explorer to make an informed decision on how best to leave Aunt Flo behind on Earth?

Now a new paper published in the journal npj Microgravity argues that as more female humans venture into space for lengthy missions, they'll need improved, current and evidence-based information on their options, especially since it's up to the individual to choose her own menstrual suppression method. Authors Varsha Jain and Virginia E. Wotring point out that from candidate selection to actual spaceflight mission, the average female astronaut will need a potential 11 years of menstrual suppression.

As it stands, most female space travelers have taken combined oral contraceptive (COC) pills during a mission. But as the paper explains, that would mean 1,100 pills for a three-year mission. Factor in packaging and that eats into the limited space and $10,000-per-pound cargo costs aboard any outgoing vessel.  

Authors Jain and Wotring note that long-acting reversible contraceptives (LARCs) such as IUDs (intrauterine devices) and subdermal implants present a safe, lighter alternative, but haven't seen much use. It's also unclear whether some of these options might snag on the inner workings of a spacesuit or shift during launch. 

But these are trivial issues compared to the effects of contraception on bone mineral density loss. Humans of either gender lose bone mass in microgravity, a factor that continues to pose a challenge to long-term human space exploration. Given the correlation between some contraceptive treatments and temporary bone mineral density loss, the authors urge further study into potential complications.

Space travel is complicated business, involving the careful study and management of everything from flatulence to near-spiritual cognitive shifts. Menstruation is just another factor we have to take into consideration.