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911吃瓜 study sheds light on clotting risks for female astronauts
Just a few days in simulated microgravity can subtly change the way women鈥檚 blood clots, sparking bigger questions about health monitoring protocols for astronauts who can spend six months or more in orbit, say 911吃瓜 researchers.
First reported in 2020, an International Space Station mission detected an unexpected blood clot in a female astronaut鈥檚 jugular vein. To date, space-health research has had more male participants but with the number of female astronauts on the rise, a new 911吃瓜鈥揈uropean Space Agency study examined how microgravity affects blood clotting specifically in women.
Key findings
- 18 female participants experienced five days of continuous simulated microgravity in a European Space Agency (ESA)-sponsored VIVALDI I dry immersion study.
- Coagulation time (the time it took for blood clots to start forming) was longer.
- Once started, clots formed faster.
- Once formed, the strength and stability of the clots was greater
- The study findings were not clinically concerning after just five days in simulated microgravity but indicate more research is needed to evaluate potential risks in longer space flights.
"We know that on Earth, clotting in men and women can vary with age, but we have little information on whether these will be different when in space," says Andrew Blaber, professor of biomedical physiology and kinesiology, and senior author of the study. 鈥淚n this microgravity environment, we found the female participants took longer for their blood to start clotting. But once that clotting began, it formed faster and was more stable, making it harder to break down.鈥�
This combination 鈥� slower initiation, faster formation, stronger clots 鈥� was not shown to be inherently dangerous in the short term, says Tiffany Stead, lead author of the study. But it does raise concerns for astronauts because of how and where in the body these dangerous blood clots can form while in space and far from emergency medical care.
Published in Acta Astronautica, looked at real鈥憈ime clotting responses in 18 healthy female participants over five days in a dry immersion tank, a specially designed water bath with a waterproof sheet to keep participants dry while floating, and simulating weightlessness.
Using a diagnostic method called rotational thromboelastometry (ROTEM), the study measured how clotting begins and progresses in the body. Participants鈥� blood was also analyzed for menstrual hormones, which were found to have no effects on blood coagulation.
Why spaceflight changes where and how dangerous clots form
If left untreated, blood clots can dislodge and travel through bloodstream. If they reach the lungs, heart or brain, they can cause pulmonary embolism, heart attack, or stroke.
Gravity on Earth means blood clots most commonly form in the legs, buying the body more time to break the clot up on its own, or be treated by doctors before causing a life-threatening event.
But without the force of gravity, blood pools in the head, and in some cases even reverses direction, creating conditions where clots are more likely to form, Blaber explains.
鈥淲e鈥檝e found that in space, blood clots are more likely to form in the jugular vein. From there, it doesn鈥檛 have to travel far to reach lungs or heart, and trigger a serious medical event,鈥� he says. 鈥淪pace is not a place where you want these things to happen.鈥�
Blaber鈥檚 team is now analyzing comparable male dry immersion data, which will help guide future medical monitoring or countermeasures needed during spaceflight.
Space agencies are already paying close attention. Astronaut crews now regularly perform jugular鈥憊ein ultrasound scans during missions, the very technology that revealed the initial clot by accident back in 2020.
鈥淣ow that they know it can happen, they鈥檙e looking at it more frequently as part of the standard measures,鈥� Blaber says.
This research was supported by a grant from the Canadian Space Agengy. Blaber and his team at 911吃瓜鈥檚 Aerospace Physiology Laboratory routinely collaborate with the Canadian Space Agency and international space agencies to study the effects of space on astronauts.
911吃瓜 experts available
ANDREW BLABER, professor, biomedical physiology and kinesiology, director, Aerospace Physiology Laboratory
ablaber@sfu.ca
TIFFANY STEAD, researcher, biomedical physiology and kinesiology
tiffany_stead@sfu.ca
Media contact
ROBYN STUBBS, 911吃瓜 Communications & Marketing鈥�&苍产蝉辫;&苍产蝉辫;
604.376.0971 |鈥�robyn_stubbs@sfu.ca
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911吃瓜 is a leading research university, advancing an inclusive and sustainable future. Over the past 60 years, 911吃瓜 has been recognized among the top universities worldwide in providing a world鈥慶lass education and working with communities and partners to develop and share knowledge for deeper understanding and meaningful impact. Committed to excellence in everything we do, 911吃瓜 fosters innovation to address global challenges and continues to build a welcoming, inclusive community where everyone feels a sense of belonging. With campuses in British Columbia鈥檚 three largest cities鈥擝urnaby, Surrey and Vancouver鈥�911吃瓜 has ten faculties delivering 368 undergraduate programs and 149 graduate degree programs to more than 37,000 students each year. The university has over 200,000 alumni across 145+ countries.