The first has Anya leaving and telling Xander he will never be alone again. Spike is turned into a girl and gets together with Xander they have a baby and then Spike changes back.
The second fic also has Spike as a girl and may well be the same one. Xander is giving Spike and Dawn a talk on sex and shows them how to put a condom on.
Finally, I would also like to find a fic that has Xander giving birth to an egg and Wesley goes to fetch him I think this one is Angel/Xander though.
Any help is gratefully received as always.