“Confidentially, he just didn’t do it for me. No matter how long we worked at it, I wasn’t feeling anything. I didn’t want to say anything and risk hurting his feelings though, you know? So finally I just faked it by screaming his name loud enough to explode his eardrums, crushing his pelvis between my thighs and clawing his shoulderblades off.”
Even without the contractions, the natural (superhuman) elasticity of the vagina would be too great to allow penetration by something as soft as an erect human penis.
If conception was achieved by some artificial method (such as carefully exposing a tiny section of the cell membrane of the ovum to kryptonite, so that the sperm can enter), if the unborn child was in any way weak like a human, the contractions of labour would crush it to death (if something else hadn’t gone wrong long before then)
Of course, we’re assuming DNA as the mating material, but even that may not be so. If mating were to occur at all, it would have to mean that Superbabe possessed normal DNA with sequences of ACGT. But this begs a question – where does super-hardness or whatever cut in? That is, Superwoman is proof against gunfire, explosions, temperatures hot enough to melt most metals, etc., probably up to and including being nuked. Well, what’s her body made of that makes it so invulnerable? Surely not the ordinary chemicals we mortals are made of. If she’s made of the same stuff as us, are the fanwankers or authors proposing some super-powerful molecular bond, or unheard-of molecular density or what? Because this woud have definite repercussions for this whole mating thing.