Given that heroes presently can conceive at will, never have accidental pregnancies or suffer from infant mortality, mpreg probably isn't too much of a stretch... (okay, okay, I assume this will get sorted out once spouses are more than placeholders. Insisting on the relative reproductive abilities of boy-shaped cardboard cut-outs and girl-shaped cardboard cut-outs seems a bit premature.)
I totally agree that most players are going to want to know gender before they name children, particularly since existing hero names conform (more or less) to Euro expectations of how suffixes connote gender. (Odds are you're not going to be calling any boys Lelia.) The alternative would be to pick culturally appropriate names from a library, which would work against player involvement a bit (Urist who?) but would reinforce the implied culture.