- Human sperm lose direction in microgravity, reducing fertilisation rates by up to 30 per cent
- Microgravity alters hormone regulation, lowering sperm and egg quality in space environments
- Cosmic radiation damages DNA and reproductive cells, raising cancer and fertility risks
A recent study has highlighted the challenges of human reproduction in space, pointing to the significant impact of microgravity and cosmic radiation on fertility. Humans have lived continuously aboard the International Space Station (ISS) for over two decades, proving that life in orbit is possible in a protected environment, though not without challenges. In microgravity, astronauts must adapt to floating conditions, specialised hygiene systems, and intense daily exercise to prevent bone and muscle loss.
Future human settlements in space are likely to rely on enclosed habitats on the Moon, Mars, or in orbit, designed to protect inhabitants from radiation and the vacuum of space. But for long-term survival beyond Earth, reproduction will be a key point. According to a study published in Communications Biology, sperm lose their direction in zero gravity, reducing fertilisation rates by up to 30 per cent.
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For the study, the researchers put human sperm into a microgravity simulation chamber, which was designed to behave like the female reproductive tract. They wanted to test the ability of the sperm to navigate.
They found that the sperm struggled to navigate through the female reproductive tract in microgravity, making it harder to reach the egg.
It is found that space radiation can damage DNA, increase cancer risk, and affect reproductive cells. Also, the microgravity alters hormone regulation, reducing sperm and egg quality.
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"As missions to the Moon and Mars move from aspiration to reality, understanding whether humans and the species we depend on can successfully reproduce in those environments is not a curiosity; it is a necessity," Nicole McPherson, the senior study author and a senior lecturer at Adelaide University, said as quoted by Scientific American.
The scientists also found that adding progesterone, which is a hormone released by the cells on a person's eggs, helped the sperm better orient.
"Progesterone works as a chemical signal, a kind of biological homing beacon that the egg releases around the time of ovulation," McPherson, who studies reproduction, explained. "Sperm have receptors on their surface that detect this signal and use it to orient themselves and swim toward the source."
"It is one of nature's more elegant navigation systems," she adds.
But she further states that the results are interesting, but "we are not at the point of suggesting progesterone as a simple fix for fertility in space".
