Fainting is a normal thing for me but that doesn't mean I can't do things to stop it.
I have a history of fainting in showers, and its because of my low blood pressure. I just had to make sure my showers weren't too hot and I never fainted in them again.
With pregnancy, I have fainted on our transit system (like a subway) 2 times, but it was almost 3 times. The 3rd time I was able to stop it from happening by getting off the train and sitting.
I have tried protein in the morning, trying to raise my blood sugar by eating something sweet, drinking water.
I had my iron levels checked and was surprised to find I wasn't anemic. But my MW said that 'normal' iron level for some isn't normal for others so she wanted me to try some Floridex to see if it helped. And it did. I don't take it everyday but maybe 4 days a week, especially on days I'll be taking the train. The train is a very crowded, hot, air tight place and I think my breathing starts to get shallow. I feel lightheaded with ringing in my ears about 3 minutes before I actually blackout. I'm usually standing because we are seriously packed in like sardines, so there isn't even room to bend down often.
I think people say its normal because there often isn't specific things wrong or that can harm the baby. But they should tell you things that might help.