When Sally Ride was preparing to be the first women in space, the male engineers worried about how many tampons to send. They estimated she needed 100. She found that number laughable and told them even half would be more than enough.
In the 33 years since Ride’s mission, more women have joined the space program and gone into space. Yet, while other bodily functions in space have been speculated about, little was known about female astronauts and menstruation. But a new study sheds light on a common practice of female astronauts—period suppression — and finds that the safest, most effective methods in space mirror those on Earth.
“Oral contraception is the best method that we know currently, on Earth, for menstrual suppression,” Dr. Varsha Jain, a visiting researcher at King’s College London’s Centre of Human and Aerospace Physiological Sciences, and an author of the study.
And, that’s true for space, too. But she was surprised to learn that long-acting reversible contraception, such as IUDs also work as well. They “have the same rates of menstrual suppression” and women using them don’t need to take a Pill daily at the same time, she says.
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Little research existed on female astronauts suppressing their periods. Turns out, many did it anyway. That’s why Jaine evaluated the current methods to identify which ones were the most effective and least likely to cause lung and leg clots.
“None of the space agencies do have regulations” on menstruation suppression, she says. But adds that reviewing the safety of these personal practices remains “quite handy” for the health of the astronauts.
While not all female astronauts suppress their periods, the rigors of training and complexities of being in space make it attractive, says Jaine. Astronauts commonly train underwater because it mimics being in space. These missions last anywhere from six to eight hours, making it impossible to change a tampon or pad.
Space comes with challenges, too. It’s difficult wrangling sanitary products in microgravity and women have less access to water in spacecraft. But being weightless does not change cramps or periods, Jaine says.
In the past, there was a misconception that women in space would experience retrograde menstruation, where the blood flows into the womb instead of it (retrograde menstruation is a possible cause of endometriosis). But she says there is no evidence of that.
“Relate it to women on Earth,” she says. “If you are laying in bed, the blood will come out of the womb. Gravity at that point doesn’t affect it. [While] being in space the uterus is expelling the menstrual flow.”
Still being in space changes periods, making this research important, says Harold Wiesenfeld, vice chair of gynecology at the University of Pittsburgh Medical Center.
"Astronauts are under stressful conditions such as microgravity, alteration in their circadian rhythm, and disruptions of their normal sleep cycle, all of which may impact menstrual regularity. It may be challenging for astronauts to deal with irregular menstruation in the midst of a mission" he writes via email.
Menstrual suppression gives female astronauts and all women who want it a safe option, if needed.
"There are no known medical risks of menstrual suppression ... [it] is an excellent approach for women with heavy or painful periods," Wiesenfeld says.
Jaine agrees and says these findings can help women in the military or other high-stress jobs. Many women in the military want menstrual suppression, but don’t know how to do it.
“We need to be looking at different populations of women who might need the [period] suppression for occupational reasons.”