A recent study conducted by the University of Adelaide showed that The ability of sperm to move It is negatively affected by the lack of gravity. The results indicate that gravity plays a vital role in the success of the fertilization process.
According to the study, starting a family life outside Earth may be more complicated than expected, as sperm have difficulty reaching the egg in microgravity conditions.
The effect of zero gravity on mobility and enrichment
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Scientists have studied how space conditions affect sperm mobility, fertilization, and early embryo development.
To test this, sperm from three species of mammals, including humans, were placed in a 3D zero-gravity simulating device known as a 3D clinostat. The device continuously rotates the cells to simulate zero gravity, distorting their orientation. The sperm were then guided through a maze that was designed to mimic the canal of the female reproductive system.
The study’s lead author said:
“This is the first time we have demonstrated that gravity is an important factor in the ability of sperm to move through ducts such as the reproductive tract.”
The results showed a significant decrease in the number of sperm that were able to reach their destination in conditions of zero gravity compared to normal gravity. The study confirmed that this was not due to a change in sperm movement itself, but rather due to other factors that affect direction determination.
The role of progesterone in improving mobility
The researchers found that adding progesterone, a hormone essential for maintaining pregnancy, helped improve the ability of human sperm to navigate in microgravity conditions.
Dr. McPherson said:
“We believe that progesterone is also secreted from the egg and can help direct sperm towards the fertilization site, but this needs to be studied further as a potential solution.”
Low fertility rates in zero gravity
The results also showed that exposure to zero gravity during fertilization reduces the number of embryonic cells. For example, after four hours of simulated zero gravity, the fertilization of mice eggs decreased by about 30% compared to normal terrestrial conditions.
Dr. McPherson explained:
“Reduced fertilization rates were observed after four to six hours of exposure to microgravity, with greater effects with longer exposure, including delayed development and decreased numbers of cells forming the embryo in the early stages.”
Why is gravity necessary for procreation?
Despite previous studies on sperm movement in space, the ability of these animals to move through the reproductive tract under controlled conditions such as these has not been tested.
These results were published in Communications Biology on March 26, 2026.
One of the professors participating in the study says:
“As we move toward becoming a multiplanetary species, understanding the impact of microgravity on the early stages of reproduction becomes critical.”
The next stage for reproductive research in space
Researchers are now moving on to study the effect of different levels of gravity, such as gravity on the Moon and Mars, and artificial gravity systems, on sperm mobility and early fetal development.
Knowing whether these changes occur gradually as gravity decreases or if there is a threshold that causes a sudden effect is essential for reproductive planning on Moon and Mars settlements, and for designing artificial gravity systems that support healthy embryo development.
Dr. McPherson added:
“In our latest study, many healthy embryos were able to form even under these fertilization conditions, giving us hope that it may one day be possible to reproduce in space.”
