If humanity truly hopes to colonize the solar system, it must overcome a challenge that may be greater than any technological obstacle: human reproduction beyond Earth. The idea may sound like science fiction, but a group of experts say they know how protecting the reproductive health of astronauts—and even make children in space—a real and pressing issue.

In a report published Tuesday in the journal Reproductive BioMedicine Onlinethese experts argue that now is the time to build a comprehensive framework governing reproductive health and space research. As the distance and duration of human spaceflight missions expand, the dangers of space increase the risks to fertility, gamete health, and embryonic development, they say.

“Although we are not promoting space births at this time, it is important to prepare for fertility risks as renewed interest in lunar missions and Mars exploration grows,” lead author Giles Palmer, a clinical embryologist and executive director of the International IVF Initiative, told Gizmodo in an email. “Space birth remains a distant prospect, but proactive planning is needed to address the biological, behavioral, and health risks that may arise.”

The reproductive dangers of spaceflight

Since the human body evolved here on Earth, it is well adapted to operate within the environmental conditions of our planet. So space is completely incompatible with our biology and physiology.

Radiation and microgravity are two of the greatest risks to astronauts’ reproductive health. “Space radiation damages DNA, interferes with gamete formation, and increases the risk of cancer, while microgravity interferes with hormonal regulation, gamete quality, and embryonic development,” Palmer explained.

Other threats inherent in the space environment include toxic dust from lunar or Martian regolith, limited resources, and chemical or microbial contamination inside a closed spacecraft, all of which can harm the health of the mother and fetus, he added. Being in space can also disrupt astronauts’ circadian rhythms—leading to hormonal imbalances and reduced fertility—and cause psychological stress that can impair reproductive function.

“In the long term, long-term exposure to these conditions can cause cumulative reproductive damage and heritable risks, including epigenetic changes that can alter gene expression and potentially affect fertility and the health of future children,” Palmer said.

Charting a safe, ethical path forward

Before scientists can address these dangers, they must fill critical knowledge gaps about them. For example, studies in animal models show that short-term exposure to radiation disrupts menstrual cycles and increases the risk of cancer, but Palmer’s review found little reliable data from astronauts returning from long-duration space missions.

While data provided by women who flew on NASA’s Space Shuttle missions showed that subsequent pregnancy rates and complications were largely unaffected, limited data was reported from men and women who flew on longer missions. Thus, there is a need for new evidence “to guide diagnostic, preventive, and therapeutic strategies in extraterrestrial environments,” the report’s authors wrote.

Future studies should aim to improve our understanding of how space hazards affect the various stages of the reproductive process, according to Palmer and his colleagues. This new knowledge will help scientists develop more effective strategies to protect the reproductive health of astronauts, such as radiation shielding, medical countermeasures, and fertility-preservation methods.

“The development of assisted reproductive technologies through AI, automation, and non-invasive tools is key for the safe use of space, along with the establishment of clear ethical standards that prioritize informed consent, transparency, gender equity, and the protection of future children,” said Palmer.

One cannot overstate the importance of these ethical guidelines as humanity expands its reach beyond Earth and advances toward in-space reproduction. But to be clear, scientists do not send pregnant people into space for research or any other purpose. Instead, they will rely on simulated environments and nonhuman models to study the reproductive risks of spaceflight, Palmer explained.

However, “entering this new frontier of research makes it important to act now by establishing an international framework and a collective review board of industrial ethics,” he said. This will not only ensure that reproductive research in space is conducted safely, responsibly, and transparently, but also protect the future of humanity as we work to establish a sustainable presence beyond Earth.

Related: Humans will never colonize Mars