modern medical forms do indeed ask for sex assigned at birth (or some variation on that) rather than gender, unless gender is specifically what they're after.

modern medical forms do indeed ask for sex assigned at birth (or some variation on that) rather than gender, unless gender is specifically what they're after. And there really is very little variation since almost everyone is part of a hospital system nowadays and literally everyone does state/insurance interactions that require specific questions/etc. OP is just being colloquial. But you are correct that there is a difference between sex at birth and gender and the medical system does handle that.