Not a bad guess though. It would be kind of a cool tie-in. Of course then the question is what happens to Sinister? Why would he know about it if he had nothing to do with it? I'd expect Sinister to bust out of captivity, but I'm not sure why.
A bunch of them are over 18.
The love child of Jean and the Professor, perhaps?
I hope that's not it. I can bare (understand even) "Xavier loves Jeannie", but a baby would be too much.
Now, I wouldn't mind seeing one of the younger ones pregnant. I know it would be a little weird, but really, what if Rogue got pregnant after the little while she could *do* stuff?...
This might be off topic but I think the couple with the best story telling potential getting pregnant would be Sue and Reed.
I definitely would not want it to be Charles and Jean because at this point I think Charles loves Jean but Jean loves Cyclops and only likes the attention from Charles.
Rogue's the only other sexually active X-Men they have I think.