przed

I think with mpreg (well, like with many many things in fic) it's in how it's written. Also, people get hung up on the biology, which is odd when you consider that in a story with a pregnant woman, there don't tend to be massive techincal descriptions. Personally I like it in situations where it's perceived as a normal, predictable event becuase then you can focus on the emotional consequences.

Or in other words, g'wan, have a go! *g*