![\"Baby](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2026\/09\/Baby-in-space-1200x801.jpeg\")
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(\u00a9 alexkoral – stock.adobe.com)<\/p>\n
In A Nutshell<\/p>\n
In a lab machine that mimics weightlessness, fewer human and mouse sperm made it through a narrow channel, even though human sperm swam with normal speed and vigor.<\/p>\n
Four hours of simulated weightlessness cut mouse fertilization by 30%, and six hours lowered pig fertilization; a high dose of progesterone restored navigation in human sperm.<\/p>\n
Human sperm that got through scored better on a lab marker of sperm quality, but mouse embryos that spent their first 24 hours in simulated weightlessness divided more slowly and had fewer epiblast cells, the cells that build the fetus\u2019s body.<\/p>\n
NASA wants astronauts back on the Moon by 2029, and SpaceX expects to send its first crews to Mars by 2030. If people ever settle on those locations for good, they will eventually need to have children there. A lab study from Australia points to an early snag in that plan: when researchers mimicked the weightlessness of space, sperm had a harder time finding their way to an egg.<\/p>\n
Scientists at Adelaide University placed sperm<\/a> from humans, mice, and pigs inside a machine that mimics weightlessness by constantly turning the samples, then challenged the cells to swim down a narrow channel. Human sperm swam with their usual speed and vigor, yet fewer of them made it to the far end. Their engines still ran, but their compass seemed to have stopped working. In mice and pigs, fewer eggs were fertilized, and mouse embryos that spent their first full day in simulated weightlessness developed more slowly.<\/p>\n Published in Communications Biology<\/a>, the findings add reproduction to a list of space health worries that already includes the muscle wasting and bone loss seen in astronauts returning from the International Space Station<\/a>. There was also a twist: human sperm that did get through scored better on a lab test linked to sperm quality. All of the work took place in labs on Earth, and no embryo was carried to pregnancy, so the results cannot yet say whether healthy babies could be conceived in space.<\/p>\n Testing sperm in space-like weightlessness<\/p>\n Researchers used a device called a 3D clinostat, which constantly turns samples to random positions on two axes. Because the sample never sits in one orientation long enough for gravity to pull it one way, the cells experience something close to weightlessness, less than one-tenth of Earth\u2019s gravity within two minutes. Machines like this are widely treated as the gold standard for mimicking microgravity<\/a> on the ground. Inside a standard incubator, the team used culture fluids and low-oxygen settings designed to resemble fertility-clinic conditions.<\/p>\n Earlier space and lab studies of reproduction produced mixed results, partly because spaceflight<\/a> experiments can\u2019t separate gravity\u2019s effects from radiation and many ground studies used less realistic lab conditions. According to the authors, theirs is the first to simulate weightlessness under conditions that mimic both the female reproductive tract and a clinical fertility lab.<\/p>\n Human sperm came from healthy volunteers between 18 and 50 years old. After a gentle wash, the sperm<\/a> were placed at one end of a tiny fluid-filled channel and given an hour to swim to the other end, either in normal gravity or on the spinning clinostat. Some trials used standard lab fluid and others a fluid designed to mimic the female reproductive tract. Tests with dyes and tiny beads confirmed that the rotation wasn\u2019t sloshing sperm down the channel; the cells had to swim there on their own.<\/p>\n Under simulated weightlessness, a smaller share of human sperm reached the far end of the channel in both fluids. Computer analysis of their movement found no change in overall motility, forward swimming, speed, or the side-to-side wobble of the head. Lost direction, not lost power, explained the drop.<\/p>\n Mouse sperm followed the same pattern. After two hours on the clinostat, fewer reached the end of the channel than in normal gravity, though the gap closed by four hours. By then, forward swimming had also begun to decline. Pig sperm kept moving normally, but something else changed. Pig sperm usually clump together heavily as they go through the chemical changes that prepare them to fertilize an egg; in normal gravity, the clumping was so heavy that researchers couldn\u2019t count how many made it through the channel. Under simulated weightlessness, that heavy clumping did not appear, which the authors say may signal a shift in how the cells work, though they did not investigate it further.<\/p>\n Progesterone steered sperm in space-like conditions back on course<\/p>\n Sperm also follow chemical signals. Cells surrounding an egg release progesterone, a hormone that triggers a flow of calcium into sperm and helps steer them toward the egg.<\/p>\n To see whether a stronger chemical signal could make up for missing gravity, researchers placed progesterone at the far end of the channel. A lower dose did not help human sperm under simulated weightlessness<\/a>. A dose ten times higher brought the share of sperm reaching the end back to normal-gravity levels, without changing how the sperm swam. That dose is far above the tiny amounts that attract sperm in the body, and the authors think the hormone may have spread too slowly through the channel during the one-hour test, which would explain why so much was needed. Still, the result hints that strong chemical cues might someday help offset the loss of gravity.<\/p>\n Fewer sperm made it, but they may have been the fittest<\/p>\n Human sperm that completed the trip under simulated weightlessness were better at latching onto hyaluronan, a substance in the layer of cells wrapped around an egg. Fertility clinics use this binding as a quality check: sperm that bind well tend to carry less DNA damage and are tied to better results after an IVF technique in which a single sperm is injected into an egg. When researchers first sorted out the strongest swimmers with a standard lab method before running the test, the binding advantage disappeared, and both groups bound equally well.<\/p>\n Fertilization<\/a> tests in mice and pigs came next. Researchers placed sperm at one end of the channel and eggs, still wrapped in their natural layer of cells, at the other, then followed about 240 mouse eggs and 400 pig eggs. In mice, four hours in simulated weightlessness cut fertilization by 30%. In pigs, six hours lowered fertilization too, and fewer of the fertilized pig eggs grew into blastocysts, the hollow ball of cells an embryo forms in the days before it implants in the womb. Mouse embryos, by contrast, reached that stage at normal rates.<\/p>\n Embryos that did form carried a surprise. Mouse embryos had more epiblast cells, the group that goes on to build the body of the fetus, even though their total cell counts didn\u2019t change. Pig embryos had more cells in the inner cell mass, the cluster that contains those future body-building cells. Higher numbers of these cells are generally considered a sign of stronger developmental potential. Researchers propose that weightlessness may act as a filter: fewer sperm<\/a> reach the egg, but those that do may be of higher quality.<\/p>\n Longer weightlessness left mouse embryos lagging<\/p>\n A separate mouse experiment kept sperm and eggs on the clinostat for a full 24 hours, so the first day of embryo life also unfolded in simulated weightlessness. With the extra time, fertilization rates matched those in normal gravity, possibly because more sperm eventually reached the eggs or because progesterone from the cells around each egg had time to spread. Embryos<\/a> paid a price. They took longer to divide from two cells to four and eight cells and ended up with fewer epiblast cells. They also trended toward fewer cells overall and fewer blastocysts forming on schedule, though those two differences were small enough that chance can\u2019t be ruled out.<\/p>\n That first day is a busy one. A single-cell embryo switches from running on material stored in the mother\u2019s egg to reading its own genes, and it undergoes major genetic and chemical reprogramming along the way. According to the authors, it is no surprise that weightlessness during this window disrupts later development. An earlier study they cite found that 24 hours of simulated weightlessness cut implantation rates by 35% after mouse embryos were transferred.<\/p>\n Why would gravity matter to a sperm cell at all? Sperm tend to hug surfaces, such as the tiny folds lining the female reproductive tract, and use them as guide rails. Changes in gravity<\/a> can knock sperm off those surfaces and scramble their orientation. Sperm also carry sensors that turn physical forces into chemical signals, and losing gravity may throw those signals off. Authors of the study say they are the first to show that gravitaxis, a response to gravity, is an important factor in sperm\u2019s ability to navigate a channel.<\/p>\n Reproduction did not stop in simulated weightlessness. Eggs were fertilized, and many embryos formed healthy blastocysts. But sperm navigation, fertilization, and early embryo growth all showed weak points, and how badly each suffered depended on the species and the length of exposure. None of these embryos was implanted, so whether they could grow into healthy offspring is unknown. Any serious plan to raise families on the Moon or Mars will need to treat reproduction as seriously as bones and muscles.<\/p>\n Paper Notes<\/p>\n Limitations<\/p>\n This study simulated weightlessness with a ground-based 3D clinostat rather than testing cells in actual spaceflight, so it did not capture radiation or other conditions of space. Its gravity bias system is proprietary technology from Firefly Biotech, and the authors acknowledge that reliance on a proprietary device may limit reproducibility. Human sperm were tested only for navigation, motility, and hyaluronan binding; fertilization and embryo development were studied only in mice and pigs, using eggs from young female mice and from pig ovaries collected at a slaughterhouse. Embryos were examined only up to the blastocyst stage, and the study did not test whether they could implant, sustain a pregnancy, or produce healthy offspring. Pig sperm swim-through recovery could not be measured accurately because of heavy clumping under normal gravity, and the absence of clumping under simulated weightlessness was not investigated further. Several embryo results in the 24-hour mouse experiment, including total cell number and on-time blastocyst formation, were trends rather than clear differences. Restoring navigation with progesterone required a dose far higher than the concentrations at which the hormone normally attracts sperm, which the authors attribute to limited diffusion across the channel during the one-hour test. In a rotational control experiment, human sperm showed a 20% decline in one speed measure (curvilinear velocity), although no such change appeared under simulated weightlessness. Molecular mechanisms behind the navigation problems remain to be worked out.<\/p>\n Funding and Disclosures<\/p>\n No funding statement appears in the paper, and the authors declare no competing interests. Corresponding author Nicole O. McPherson lists affiliations with Genea (Sydney) and Fertility SA, Powered by Genea (Adelaide), both clinical fertility organizations. In the acknowledgements, the authors thank Giles Kirby, CEO and founder of Firefly Biotech, the company that makes the clinostat used in the study, and Ian Johnson for expertise on the device and on culturing cells under simulated microgravity.<\/p>\n Publication Details<\/p>\n \u201cSimulated microgravity alters sperm navigation, fertilization and embryo development in mammals\u201d was written by Hannah E. Lyons, Victoria Nikitaras, Bridget M. Arman, Stephen M. McIlfatrick, Mark B. Nottle, Macarena B. Gonzalez, and Nicole O. McPherson. Authors are affiliated with the Robinson Research Institute, the Freemasons Centre for Male Health and Wellbeing, the Discipline of Reproduction and Development in the School of Health, and the Andy Thomas Center for Space Resources, all at Adelaide University in Adelaide, Australia, as well as Genea (Sydney) and Fertility SA, Powered by Genea (Adelaide). It appeared in Communications Biology,<\/a> a Nature Portfolio journal, as volume 9, article 401 (2026). It was received on August 5, 2025, accepted on February 10, 2026, and published online on March 26, 2026. DOI: 10.1038\/s42003-026-09734-4. Correspondence: Nicole O. McPherson ([email\u00a0protected]<\/a>).<\/p>\n","protected":false},"excerpt":{"rendered":"(\u00a9 alexkoral – stock.adobe.com) In A Nutshell In a lab machine that mimics weightlessness, fewer human and mouse…\n","protected":false},"author":2,"featured_media":908508,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[64,63,96405,58674,16836,3189,2725,326,476569,128,285,42592,89203],"class_list":["post-908507","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-au","tag-australia","tag-babies","tag-conception","tag-fertility","tag-gravity","tag-mars","tag-outer-space","tag-procreation","tag-science","tag-space","tag-space-travel","tag-sperm"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/908507","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=908507"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/908507\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/908508"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=908507"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=908507"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=908507"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"An](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2026\/09\/Sperm-in-space-study-1200x850.jpg\")
An Adelaide University study has found the navigational abilities of sperm are negatively impacted by a lack of gravity. (Credit: Sperm and Embryo Biology Laboratory, Adelaide University)<\/p>\n![\"Exposure](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2026\/09\/Eggs-in-space-study-1200x595.jpg\")
Exposure to zero gravity appeared to modify the number of fetal cells within the embryo. (Credit: Sperm and Embryo Biology Laboratory, Adelaide University)<\/p>\n