Space tourists will probably have sex up there, but they shouldn't get pregnant, researchers warn

• Space tourism is blasting off. Virgin Galactic just flew its first tourist crew, with plans for monthly trips.
• If someone gets pregnant in space, the radiation could harm them or their embryo, scientists say.

Let's talk about space sex.

So far there have been no reports of cosmic coitus, but more and more people are taking a pleasure cruise in Earth's orbit. It may just be a matter of time until somebody starts the 250-mile-high club.

Since billionaires Jeff Bezos and Richard Branson raced to the edge of space two years ago, orbital tourism has taken off.

Branson's company, Virgin Galactic, successfully flew its first space tourists on Thursday, and plans to conduct similar flights every month.

SpaceX launched its third batch of people who aren't professional astronauts into space in May.

Billionaire Yusaku Maezawa has booked a trip around the moon on the company's Starship mega-rocket, which made its first attempt at launching to orbit in April. Entrepreneur Dennis Tito has booked two seats on a similar Starship lunar flight — one for himself, and one for his wife.

If they can shell up enough cash, wealthy people around the world can book a vacation beyond it, lasting anywhere from a few minutes to a few weeks. Some companies even aim to build hotels in Earth's orbit.

"It is unrealistic to assume that all space tourism participants will abstain from sexual activities," researchers wrote in a green paper on the subject earlier this year.

That's why, they argue, spaceflight companies should be proactive and talk to their customers about cosmic coupling and its risks.

If somebody gets pregnant — on purpose or otherwise — there's a chance that the background radiation of space would harm a freshly fertilized egg cell, even if they're only in space for a day or two after the act, two space researchers told Insider. There's no telling how that would affect the rest of the pregnancy.

"These high-energy deep-space-radiation particles, some of them pass right through the vehicle and right through people. And so in theory, if one of them is coming through and it just so happens to hit a developing embryo, what effect would it have on that?" Dr. Kris Lehnhardt, who leads NASA research on medical systems for deep-space exploration, told Insider.

That's an open question, Lehnhardt said, but "the consequence of someone becoming pregnant in space could be very high."

The dangers of unfettered space fornication

It may not even be possible to get pregnant in space, but it's probably not worth taking the chance.

There has been very little research on the effects the space environment might have on reproductive systems. That's partly because space research has long been dominated by government agencies.

"In general, NASA stays away from sex and reproduction questions," Lehnhardt said. "It's not truly relevant to the work that we're doing at NASA right now on a day-to-day basis."

Even when it has been relevant, reproductive health hasn't been one of NASA's strong suits. Engineers there famously asked astronaut Sally Ride if 100 tampons would be enough for a one-week spaceflight.

Most of the space reproduction studies that do exist are focused on rodents. Their findings may not be applicable to humans at all, but they offer hints that reproductive functions could be affected by space radiation and microgravity.

In one study, researchers put mouse embryos in an incubator on board a satellite. The embryos developed in space but sustained "severe" DNA damage and had developmental defects.

In other research, exposure to microgravity decreased testosterone levels and sperm production in male rats. Some female rats have mated during spaceflight but then shown signs of early pregnancy loss.

Some forms of radiation on Earth are known to have negative effects on human pregnancy. But "the galactic cosmic radiation that we experience in space doesn't have a good comparison on the ground," Lehnhardt said.

It may even be risky to conceive within a few months of returning from spaceflight, the green paper authors argue. Again, research is lacking. The uncertainty is enough for some astronauts to freeze their eggs before they launch into orbit, according to Lehnhardt.

Have you talked to your spaceflight customers about sex?

If someone does get pregnant up there, that person or their fetus could face complications. Failure to address this possibility puts space-tourism companies at risk of reputational damage or litigation, the green paper argues.

"We're definitely not trying to say you should ban sex in space," David Cullen, the lead author of the paper and a professor of space biotechnology at Cranfield University, told Insider.

Instead, he continued, companies should "put in place procedures and mitigations to minimize the chance of any sexual interactions leading to human conception."

Cullen and his co-authors argue that space-tourism leaders should talk about the risks of acting on orbital arousal. Companies could require that their customers undergo medical and reproductive counseling, or sign waivers about sex and reproduction before flying.

To build cities on other planets, we have to learn how to make babies out there

Those are just the first steps. If humans are to settle on other planets to become a "multiplanetary species" — a goal that Elon Musk has often touted over the years — someone will need to figure out the feasibility and risks of space sex, pregnancy, and birth.

That's why Cullen and other authors of the paper are working on an initiative called SpaceBorn United, to research in vitro fertilization (IVF) in space. The company plans to try space IVF first using mouse embryos, in 2024, but eventually aims to test on human embyros.

"Those are the stepping stones of research that would be needed to see how viable pregnancy could be in the space environment," Lehnhardt said.

But, he was sure to note, "NASA has absolutely nothing to do with that."

This post has been updated. It was originally published on August 9, 2023.