My cat was an inside cat for about 3-4 years, with the occasion where she would slip past you and run all the way to the end of the yard, now she is a fully fledged outside (inside when she feels like it) cat. They might disappear for a bit but they will always come back when it's hungry. I could always get my cat to return no matter where she disappeared off to, by shaking her food bax, 5minutes later she was rushing to her food bowl
Hope this helps And good luck with your kitties and your new baby on the way