Donating blood in early pregnancy?

Question

I've always wondered what would happen if a woman, who did not know she was pregnant at the time, donated blood. You read everywhere that pregnant women should not donate, and they even ask you if you have been pregnant with in the past 6 weeks during the interview part of donating blood. But what really happens to the woman/fetus if you donate blood before you know you are pregnant?
This is simply out of curiosity- no underlying issue. Thanks!

Answer 1

I am not an expert but I agree that blood pressure would be affected more and that she would be more likely to feel faint/dizzy.

I would imagine that the blood service would ask routinely if there is any chance.

I doubt there would be a huge risk for a healthy young expectant Mum who gave blood not realising. It must relate to how quickly the blood taken can be replaced in their system. She would probably take longer to recover from the donation.

Answer 2

I'm not a doctor, but, I'm sure the womans blood pressure would drop, causing her to feel lightheaded and nauseous, she might even start to have "tunnel vision" or faint.