this is along with name, race and other demographic information
They don’t have a gender field, and it really feels like they are just reducing sex and gender down to “you are what you were assigned at birth”, and then hiding behind amorphous medical “reasons” as justification …
If you were intentionally trying to design the page in a way to deny trans people their identity, I don’t know what you would do differently from this.
A binary ‘Sex’ field could at least have the cover of “Sorry, the code is 30 years old and we don’t know how to change this field in the database without breaking things.” Labeling the field as Sex Assigned at Birth means they considered trans people and considered them worth hurting.
Edit: I do think asking for sex is a CDC thing. But only asking that means you can be misgendered at the pharmacy and also ignores that hormones have a major role in your health. A doctor or pharmacist going off your birth certificate to treat you is a bad doctor/pharmacist.