Wow, Dave, that's fantastic! Congrats to Mrs. Dave! What a cool development - I'm happy for you (and happy/hopeful for me!).
As for the "we did it while dating but not now" thing, it may have to do with the increasing-importance thing. The two of you are VASTLY more important to each other now than during the dating phase, esp. since DD came along, so it will probably take some further differentiation for both of you to feel comfortable ML during "that time of the month"... I have NO doubt you'll get there, tho...