Months ago he wanted to know where he was before he was born. Since it's not something I can really wrap my head around, I told him that the angels were watching him until his Daddy and I were ready to take care of him.
I also recently had a relative pass away, and we've never been the type of parents to dumb things down for the boy, and he's not really the kind of kid that will take the dumbed down version anyway. So when my Aunt passed away - I hope when I'm 96 I have all my faculties till the end! - we explained him that she had died and it was time for her to go to be with Jesus. He had a ton of questions and we talked about it a lot.
So getting back to the other day, I explained to him again that they were only watching him until it was time for him to come to us. Then he asked, "But what if you never had me?" Holding back tears, I responded, "...I would have done anything to have you!"
...and that's when I realized that IVF was just my method of "anything" to get the rest of my babies from the angels. It's amazing the things your little one can make appear so clearly.