Humanity’s greatest challenge in becoming a multi-planet species may not be building bigger rockets or landing astronauts on Mars. Instead, it could come down to the question: Can humans safely conceive, carry pregnancies, and raise healthy children off Earth?
A new review published in Frontiers in Space Technologies argues that the answer to this question remains unclear. Drawing on decades of research on animal reproduction in space alongside emerging advances in artificial intelligence, biotechnology, synthetic biology, and cybernetic systems, the researchers suggest that future generations born off Earth may require technologies far beyond today’s medical capabilities.
In the most speculative sections of the paper, researchers even envision a scenario in which reproduction itself acts as a tool for helping humans gradually adapt to life in space.
Rather than presenting new experiments, the paper synthesizes existing evidence while outlining possible technological pathways that could someday enable permanent human settlements on the Moon, Mars, or even deeper into the solar system.
The central message is that surviving in space is only the first hurdle. Establishing self-sustaining civilizations will ultimately depend on whether human reproduction can succeed under conditions of microgravity, radiation, isolation, and other environmental stresses that evolution never prepared us to face.
“It is proposed that prenatal and early postnatal developmental stages may constitute critical biological windows for facilitating long-term adaptation to space,” researchers write. “Such interactions could ultimately transform reproduction and early development into active drivers of human evolution, contributing to the emergence of biologically distinct populations progressively adapted to diverse space environments.”
Despite more than six decades of human spaceflight, no human has ever conceived or carried a pregnancy in space. Therefore, science has little direct evidence about what would happen if astronauts attempted to start families off Earth. Nearly everything researchers know comes from studies involving animals ranging from sea urchins and fish to frogs, birds, mice, and rats.
The results are encouraging in some respects but troubling in others.
Several non-mammalian species have successfully reproduced in orbit. Medaka fish, for example, became the first vertebrates to reproduce in space, with fertilization rates comparable to those seen on Earth. Yet, even when reproduction occurs successfully, researchers have documented developmental abnormalities in some species, suggesting that space environments can slightly modify embryonic development.
Rodent studies paint an even more complicated picture. Fertilization is not impossible under microgravity, but early embryonic development frequently suffers. Experiments have shown reduced blastocyst formation, slower embryo development, lower live birth rates, and changes in gene expression. Other studies have linked space radiation to DNA damage, genomic instability, and developmental defects affecting the nervous system.
At the same time, some findings show surprising resilience. Mouse embryos cultured aboard the International Space Station have developed into apparently normal blastocysts under certain conditions. In contrast, freeze-dried mouse sperm stored in orbit for months later produced healthy offspring after returning to Earth.
These mixed findings suggest that reproduction may be biologically possible, but far from routine, under space conditions.
In their review, researchers also examined growing evidence that spaceflight affects male and female reproductive health even before conception occurs.
Microgravity and radiation appear capable of disrupting sperm production, reducing testosterone levels, altering ovarian function, impairing egg maturation, and interfering with hormone regulation.
Some studies suggest sperm can still swim under simulated microgravity, but lose their capability to navigate effectively toward an egg. Others report that radiation accelerates the depletion of ovarian follicles and increases DNA damage in reproductive cells.
More concerning is the possibility that some biological changes could be passed to future generations through epigenetic mechanisms. Experiments involving mice have suggested that spaceflight may alter gene regulation in sperm and influence gene expression in offspring, although the long-term significance is still unknown.
For women, pregnancy itself could present an even greater challenge. On Earth, pregnancy requires profound cardiovascular changes that help deliver oxygen and nutrients to a growing fetus. Microgravity, however, causes fluid redistribution, muscle loss, reduced blood volume, bone demineralization, and changes in cardiovascular function that could interfere with placental development and fetal growth. Radiation exposure, oxidative stress, circadian disruption, and limited medical support would only add to those risks.
Researchers argue that simply shielding astronauts from radiation may not be enough. Gravity itself appears to function as a biological signal that influences everything from cell organization to tissue development. That realization carries renewed interest in artificial gravity as a potential solution.
Instead of depending solely on habitats built on the Moon or Mars, future space settlements could include rotating structures that generate centrifugal force to recreate Earth-like gravity.
Such habitats have appeared in science fiction for decades, but researchers suggest they may ultimately become essential for healthy conception, pregnancy, childhood development, and multigenerational life off Earth.
Researchers propose dedicated orbital research platforms where scientists could systematically study reproduction under lunar, Martian, or custom-designed gravity levels before humans attempt permanent settlements.
Artificial intelligence also features prominently in the researchers’ vision of the future. They propose AI-powered “digital twins” capable of integrating biological, physiological, and environmental data to simulate how embryos, pregnancies, and developing children might respond to different gravitational and radiation environments. These computer simulations could help researchers examine scenarios that would be difficult, or ethically impossible, to test directly in humans.
Perhaps the paper’s most futuristic proposal is something the researchers call Synthetic Reproductive Adaptive Enhancement Technology, or SRAET. This speculative concept envisions highly automated reproductive systems combining artificial wombs, advanced reproductive biotechnology, biosensors, AI-assisted monitoring, and predictive developmental modeling into a closed-loop environment capable of supporting conception through birth under carefully controlled conditions.
The framework explores the controversial possibility that future advances in gene editing and synthetic biology could one day help humans adapt biologically to off-world environments.
Researchers emphasize that such ideas are still speculative and acknowledge the enormous ethical, biological, and safety concerns surrounding germline modification, off-target mutations, and multigenerational consequences. Rather than advocating immediate implementation, they present these possibilities as conceptual pathways that justify careful scientific and ethical discussion.
For fans of science fiction, many of these concepts may sound remarkably familiar. Yet, researchers attempt to ground their arguments in existing developmental biology, reproductive medicine, aerospace engineering, and space medicine while clearly distinguishing current evidence from future speculation.
In the end, researchers suggest that the future of human space travel may depend less on propulsion systems than on understanding how life develops under entirely new environmental conditions. If humanity hopes to establish permanent settlements off Earth, science will first need to ensure that future generations are able to begin life safely under alien skies.
“Ultimately, the greatest challenge of human expansion beyond Earth may not be transporting humans into space, but understanding how life itself can develop, adapt, and evolve under space conditions,” researchers write. “In this sense, SRAET would not merely support reproduction beyond Earth; it would represent a developmental biotechnology through which humanity may begin to actively participate in shaping its own evolutionary future.”
Study: Ferraz M, Moeharram L. “Past, present and future of human reproduction and development in space.” Frontiers in Space Technologies. 2026.
Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan. Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com