New Delhi: Microgravity in space may impact reproduction, with sperm losing their navigational ability once they’re beyond Earth’s gravitational pull, a new study has found.
The recent study was published in Communications Biology. The research, led by Nicole McPherson at Adelaide University, used a 3D clinostat—a device that simulates near-zero gravity. The aim was to observe what happens to sperm from humans, mice and pigs as they attempt to navigate toward an egg. They also observed what happens to embryos in the earliest hours after fertilisation.
The study shows reproduction beyond Earth is easy to disrupt.
One of the study’s clearest conclusions is that sperm tend to lose their direction in microgravity. For this, the sperm were placed in micro-channels designed to mimic the female reproductive tract. It was observed that far fewer sperm were able to navigate their way through under simulated space conditions. This happened across the three species.
However, this was not because sperm swam more slowly or moved less. Their speed and basic motility remained the same, but the movement was not toward the egg.
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Progesterone restores sperm navigation
Human sperm did show one intriguing loophole. Researchers found that the addition of a high dose of progesterone—a vital steroid hormone produced primarily in the ovaries, adrenal glands, and placenta—can restore the navigation ability of sperm. This suggests that reproduction in space might require chemical or environmental boosters to compensate in the absence of gravity. “Progesterone partially restored navigation in human sperm under microgravity, suggesting the potential of chemical cues to mitigate gravitational absence,” the research states.
In mice, microgravity not only reduced fertilisation success but also affected the embryos. After four hours of fertilisation under simulated microgravity, fertilisation rates had dropped by nearly 30 per cent. Yet, the embryos that developed showed an unexpected change: they had more epiblast cells—the cells that eventually help in the formation of tissues.
However, prolonged exposure to microgravity can hinder early growth, as mouse embryos kept in microgravity for 24 hours after fertilisation showed developmental delays and a lower total cell count.
Pig embryos also showed altered development, with reduced progression to the blastocyst stage (a ball of cells that forms early in a pregnancy) when fertilised in microgravity.
The implications go far beyond lab curiosity. NASA’s Artemis program aims for long-term lunar presence by 2029, and private companies are projecting human missions to Mars within the next decade.
This study is among the first to rigorously recreate clinical IVF conditions under simulated microgravity, offering a clearer picture of what reproduction in space might look like.
(Edited by Saptak Datta)