Right now, you’re able to select the appropriate gender marker on your passport without a note from a medical professional (and a passport can be used in the vast majority of situations you’d use a birth certificate) but because the self select gender marker was done by executive action, it’s extremely likely to be reversed when Trump takes office.
Also, having one might be a good idea in general.
IIRC it’s a lot harder (legally and practically, because figuring out which applicants are transgender requires sifting through paperwork) for them to invalidate passports that have already been issued. I got my first passport before the first Trump term with my correct name and gender on it and had no issues, but all the paperwork went through during the last days of the Obama admin. I do remember hearing about people having trouble getting the right passport after he came into office. So if you want it and can afford to pay to rush it, it’s not a bad idea.
Edit: I would say that probably the people most in danger of having their passports invalidated soon after he takes office are people with X for their gender marker. That would be much more simple than invalidating every trans person’s passport that has an M or F on it.
That’s good to know. I’m definitely gonna rush to get all of my docs changed after I get my certificate of name change in the mail. Unfortunately can’t get my birth certificate changed because of the state I was born in.