Invisible Crib Mod

Are you using mods(of any kind) or maybe a CC crib? Try moving them to your desktop then testing to see if the problem occurs. If not, try adding your mods back to your newly generated mods folder in small batches and checking again for the problem. Keep going until you find the culprit. I would suggest making a save with a sim in their 3rd trimester and exiting without saving after each trial so that they are always ready to give birth.

Also try deleting your localthumbcache.package file (as it bloats with animations) and your cache. The game will generate new files.

My sim is pregnant for another 12 days, so I can't test a home birth with the invisible crib at the moment. But I can say I haven't had any issues with it yet. I also always use the hospital to deliver since you get a neat lil birth certificate if you do.