Giving birth to a baby in space may require a little more direction. New research from the University of Adelaide has revealed that sperm’s ability to navigate is negatively affected by the lack of gravity.
Researchers from the university’s Robinson Research Institute, School of Biomedical Sciences, and Freemason Center for Men’s Health and Welfare investigated how extraterrestrial conditions affect sperm navigation, fertilization, and early embryo development.
Sperm samples from three different mammals, including humans, were passed through a 3D clinostat device developed by Dr. Giles Kirby of Firefly Biotech. The device simulates the weightlessness experienced in space by inverting cells, causing disorientation. The sperm then traveled through a maze designed to mimic the female reproductive tract.
This is the first time we have been able to demonstrate that gravity is an important factor in the ability of sperm to pass through channels such as the reproductive tract. ”
Dr Nicole McPherson, Robinson Research Institute, University of Adelaide Senior Author
“Under microgravity conditions, we observed a significant reduction in the number of sperm that successfully passed through the chamber maze compared to normal gravity conditions.
“This was correctly experienced in all models despite no change in the way the sperm physically moved. This shows that the loss of sperm orientation is not due to changes in motility, but to other factors.”
The addition of the sex hormone progesterone, which is important for the establishment of pregnancy, allowed more human sperm to overcome the negative effects of simulated microgravity on navigation.
“We think this is because progesterone is also released by the egg and helps guide sperm to the fertilization site, but this requires further research as a potential solution,” Dr McPherson said.
The researchers also examined the effects of exposure to microgravity during fertilization on embryo development in animal models.
They observed a 30 percent reduction in the number of mouse eggs that were successfully fertilized after four hours of exposure to zero gravity compared to typical conditions on Earth.
“We observed a reduction in fertility after four to six hours of exposure to microgravity. Longer exposures appear to be even more harmful, slowing development and, in some cases, reducing the number of cells that will form a fetus during the early stages of embryogenesis,” said Dr. McPherson.
“These insights demonstrate how complex reproductive success in space is, and the great need for further research throughout the early stages of development.”
Previous studies have examined sperm motility in space, but no previous studies have assessed the ability of sperm to transit the reproductive pathway under these controlled conditions.
The results of this study are communication biology (Nature Portfolio).
The research is also a collaboration with the University of Adelaide’s Andy Thomas Space Resources Center, which focuses on long-term planetary exploration and meeting the challenges of living in extraterrestrial environments.
Associate Professor John Culton, director of the Andy Thomas Space Resource Center, said: “As we move closer to species traveling through space and living on multiple planets, it is important to understand how microgravity affects the early stages of reproduction.”
Researchers are now in the next stages of investigating how different gravity environments, including the Moon, Mars, and proposed artificial gravity systems, affect sperm navigation and early embryo development.
An important question is whether gravity-related developmental changes occur gradually as gravity decreases, or whether there is a threshold effect, an “all-or-nothing” response.
Understanding this difference is essential for planning future human reproduction in extraterrestrial environments, including settlements on the Moon and Mars, and for designing artificial gravity systems that support healthy development.
“In our latest research, we were still able to form many healthy embryos when fertilized under these conditions. This gives us hope that reproduction in space may one day be possible,” Dr Macpherson said.
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Reference magazines:
lions, he, others. (2026). Simulated microgravity alters sperm migration, fertilization, and embryonic development in mammals. Communication biology. DOI: 10.1038/s42003-026-09734-4. https://www.nature.com/articles/s42003-026-09734-4
