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.
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.