Why do I tell father about birth?

I posted about this before but the two responses I got seemed to misinterpret what I meant.

I don’t plan on having the father at the hospital while I give birth we’re not currently on speaking terms or even in the same state.

I just want to know how long after I give birth do I have to tell him about baby being born ? Ex: when I go into labor, the next day, a week, when I’m ready for home visitors.

Original post for details in photo.

Thx