Just had a moment to do some quick testing. I did a clean install of the game and applied my Navigation Information Combo patch. Then I turned on the Pregnancy mod and everything worked fine for me. So my guess is that it is an install problem.
The game's mod system is certainly a bit quirky. It creates backup versions of files and some things trigger the backup files to be copied back over the game's files. It's possible the game did this and replaced/edited a needed file.
If you are still having trouble, I'd suggest doing a clean install.
1. Turn off all mods.
2. Unzip the game into a new directory. (delete/or don't, the existing game folder, but do not extract the clean installation over the top of the existing game)
3. Drop in my patch mod (any single one of my Info Mod, Nav Mod, or Nav-Info Combo).
4. Start game and turn on Pregnancy Mod.
5. Restart game and play.