No Babies in Space

At least in Zero-G. [Link]

Any future astronauts here who are hoping to make the first space baby might want to think again - embryonic stem cells don't act the same way in zero gravity, making successful procreation in space almost impossible.

We already know that full-grown adults suffer harmful consequences the longer they stay in microgravity, as prolonged living in zero-G causes muscles and bones to weaken and an irregular heartbeat. But the dangers also operate on much tinier scales as well, as a team of Australian researchers have now discovered. Microgravity tampers with stem cells, the building blocks of all other cells in our body and a vital repair system.

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.