It's almost surprising it hasn't happened already: someone getting pregnant in space. I mean, we've got astronauts of both sexes hanging out up in the International Space Station, so what's the holdup? Well, whatever the reason, it turns out it's probably for the best.

That's because it turns out that embryonic stem cells don't behave the same way in zero gravity that they do here on Earth:

The researchers simulated zero-G conditions on Earth and then placed embryonic stem cells inside. They discovered that 64 percent of the stem cell proteins were fundamentally different from how they would be in normal gravity. And the changes weren't good - most of the altered proteins would weaken bones and allow increased oxidative damage to DNA. Damage was also done to proteins involved with the immune system, proper cell division, calcium levels, and much more.

Yikes! OK, so pregnancy in space is out. Sex in space, however, still seems safe. Let's get on that, astronauts. It's for science.

Space.com via io9