Pregnancy tracking app for a kid?

My son wants an app that lets him track fetal development throughout my pregnancy. I would download Glow for him if not for the forums. But, obviously I don't want him to have access to everything that is discussed here.

I thought there might be an app for siblings to track new baby's progress, but I can't find one. And I definitely don't want anything that isn't factual or will dumb things down for him.

He's ten, but he knows where babies come from. Sex, pregnancy, and childbirth are not foreign concepts to him, so I would allow him to use a more mature app as long as he isn't able to come into contact with people.

Suggestions?