mobile.twitter.com/LGBTLD/status/979423663547146240
If you scroll down a little bit, the person on the LibDem twitter account (a transwoman I think) says they filled in the female question when they gave blood.
People underneath are saying it could be dangerous - I know nothing about this area, I'm sure there will be a MNer with expertise in this. If not dangerous then maybe more implications than they have thought about? Genuinely not trying to scaremonger. My biology knowledge is minimal.