A Guardian writer warns women against getting pregnant while en route to Mars:
The problem Straume and his colleagues focused on was cosmic radiation. Without the protection of the Earth’s magnetic field, space travellers would be bathed in high-intensity radiation on a trip to Mars, a journey that would take eight months with today’s technology. These energetic particles smash DNA and would likely increase cancer rates, but the radiation might also cause enough genetic damage that babies would be born infertile, the scientists conclude.
If that didn’t get your attention, let me point out there’s also some discussion of sex in space.