How long can an astronaut stay in space and later have children?

Question

While reading about the effects of microgravity on reproduction I was thinking about all the other aspects of space flight and how they may decrease fertility in both men or women (such as changes in cardiovascular health, radiation, the effect of microgravity on menstruation and possibly ovulation, etc…).

I realize that most astronauts are on the older side and usually already have families which will make having children less common and so a negative result doesn't mean much. The duration in space would of course be one of the most important factors, so I realize mentioning Joe Starman who spent 8 days on STS-XXX isn't really that useful. I'm just interested in the longest-term examples of astronauts (male or female) who successfully had a child after being returning from space, as that would give a very general example of the possibility.

Answer 1

I'm pretty sure this is not the answer you wanted, but... given the right preparation, indefinitely. Semen and ova can be extracted, and stored cryogenically for a long, long time; the storage is small enough to shield it efficiently against cosmic radiation too, even if it were to be sent to Mars, and the in-vitro procedure has been studied and advanced sufficiently that it could be performed 'in space colony conditions'. So, while plain old sex might not work, there is still an efficient workaround.

A separate problem is theorized (please excuse me for not providing the source, it's been a while since I read this and don't have it readily available): humans are not easily rendered sterile by cosmic radiation, but it is expected that the radiation may damage the ova in such a way that the offspring is born infertile. The period of exposure and likelihood of such damage haven't been determined yet.