I didn't want to thread jack, but this comment got me thinking
My 5-year-old started asking me the day I got my BFP if there was a baby in my belly. It was kinda creepy.
DS1 was 2 1/2 when I got pregnant with #3 and he actually mentioned a baby in my tummy the day before my BFP (which I got at 10dpo). Fast forward to a few days ago. I finally got to that first PP ovulation. I O overnight and the next morning the first words DS1 said to me were "Mommy, is there a new baby in your tummy?" If he's right I'm hiring him out as a psychic. (I'm expecting a short LP because I'm BFing and we've been preventing.)