Presumably he already has told them his number and preferences. Defaults are fine, but you don't want your preference to get reset to default every time, and assuming that only the mother of a child should be contacted in all cases is a terrible default. The person who made the appointment and who is bringing the child to the doctor should be the one contacted by default. There is no reason that the mother of a child should be considered the default guardian. That is an incredibly dangerous assumption to make in many circumstances.

Edit: This reply was written to a response that got completely rewritten in an edit. It may not make as much sense

This. Don’t be so sensitive, just say to call you.

I took my daughter to appointments and as soon as I started asking meaningful questions, doctors immediately switched to assuming I was the one to talk to.

When you act like you know what’s going on, act like you’re on top of it, I’ve never once had a doctor assume I was just babysitting. This was true in the Midwest and California.

> doctors immediately switched to assuming I was the one to talk to.

Exactly! They do that. If a father takes the kid, they will ask for his number, not the mother's, in my experience. If both the mother and father goes with the kid, well, there are cues they pick up on. In my case my father typically was always in the background while my mother was the one doing the talking, meaning they ask for her number, not my dad's. So, all in all, whoever does the most talking, for example. And if my dad wanted to be the one called, my mom would have told them his number, or my dad would have. I do not see an issue here really.