So I agree that pregnancy, cancer risks, etc. are all relevant, and even that you can make some reasonable inferences based on assigned sex at birth (ASAB), but you run into trouble when that’s the only question that is asked.

For example, breast cancer is a risk that trans women face just like cis women, a biological fact that is ignored when only ASAB is considered … Trans women also have far lower risks of prostate cancer than men, so cancer screening looks different in trans women than cis men (including even the way that a prostate would be accessed, in the case of post-op trans women).

Only asking for assigned sex at birth is a form of discrimination in several ways. For one, it doesn’t allow someone to identify or disclose gender, they ask for race and other social characteristics but for gender the only field is assigned sex at birth.

This means a person’s gender is inferred from their ASAB, making it clear discrimination against trans people who have a gender that isn’t aligned with their assigned sex at birth, i.e. it’s a prejudicial denial of trans identity.

It is also discriminatory against some intersex people who are (and were born) neither male nor female.

If biology masters in healthcare, then they should be asking questions about your biology, not a social category that everyone has been assigned based on quick glances at genitals and in complete defiance of the reality of biological sex.