OP put off saying anything about for 5 years, and now feels that 2-mo post-birth is now the perfect time to have this discussion?
Hopefully this isn’t the case, there isn’t enough information here to say one way or another, but it certainly gives the appearance of attempting to trap the partner in the relationship with the child. It’s a common tactic of abusers.
Avalon
https://en.wikipedia.org/wiki/Avalon