Starting a family beyond Earth may very well be tougher than expected. Recent research from Adelaide University shows that sperm struggle to navigate in low gravity, suggesting that gravity plays a key role in helping them reach an egg.
Scientists from the Robinson Research Institute, the School of Biomedicine, and the Freemasons Centre for Male Health and Wellbeing studied how space-like conditions affect sperm navigation, fertilization, and early embryo development.
To simulate microgravity, researchers used a 3D clinostat machine developed by Dr. Giles Kirby at Firefly Biotech. This device repeatedly rotates cells to mimic the disorienting effects of zero gravity. Sperm from three different mammals, including humans, were tested by sending them through a maze designed to resemble the feminine reproductive tract.
“That is the primary time we’ve got been capable of show that gravity is a vital consider sperm’s ability to navigate through a channel just like the reproductive tract,” said senior creator Dr. Nicole McPherson from Adelaide University’s Robinson Research Institute.
“We observed a big reduction within the variety of sperm that were capable of successfully find their way through the chamber maze in microgravity conditions in comparison with normal gravity.
“This was experienced right across all models, despite no changes to the best way sperm physically move. This means that their lack of direction was not attributable to a change in motility but other elements.”
Progesterone May Help Guide Sperm
The researchers also found that adding the sex hormone progesterone improved how well human sperm navigated under simulated microgravity conditions.
“We imagine it’s because progesterone can be released from the egg and might help guide sperm to the location of fertilization, but this warrants further exploration as a possible solution,” said Dr. McPherson.
Fertilisation and Embryo Development Affected
The team examined how exposure to microgravity during fertilisation influences early embryo development in animal models.
After 4 hours in simulated zero gravity, the variety of successfully fertilized mouse eggs dropped by 30 per cent in comparison with normal Earth conditions.
“We observed reduced fertilization rates during four-to-six hours of exposure to microgravity. Prolonged exposure seemed to be much more detrimental, leading to development delays and, in some cases, reduced cells that go on to form the fetus within the earliest stages of embryo formation,” said Dr. McPherson.
“These insights show how complex reproductive success in space is and the critical need for more research across all early stages of development.”
Why Gravity Matters for Reproduction
Earlier research has explored how sperm move in space, but none had tested their ability to navigate through a reproductive channel under controlled conditions like this.
The findings were published in Communications Biology.
This study was conducted in collaboration with Adelaide University’s Andy Thomas Centre for Space Resources, which focuses on the challenges of long-term space exploration and living beyond Earth.
“As we progress toward becoming a spacefaring or multi-planetary species, understanding how microgravity affects the earliest stages of reproduction is critical,” said Associate Professor John Culton, Director of the Andy Thomas Centre for Space Resources.
Future Research on Reproduction in Space
The subsequent phase of the research will explore how different gravity environments, including those on the Moon, Mars, and in artificial gravity systems, affect sperm navigation and early embryo development.
A key query is whether or not these effects change regularly as gravity decreases or if there may be a threshold where changes occur suddenly, creating an “all or nothing” response.
Answering this will likely be essential for planning human reproduction in future Moon and Mars settlements and for designing artificial gravity systems that support healthy development.
“In our most up-to-date study, many healthy embryos were still capable of form even when fertilized under these conditions. This provides us hope that reproducing in space may someday be possible,” said Dr. McPherson.