Hi Jan, low blood pressure (and therefore fainting) can be a feature of PG for some women. I have read around the boards that if you are a bit dehydrated that can cause your blood pressure to drop, so it's really important to drink LOTS of water.

When you think you are going to faint try to get your head down lower than your heart (between your knees if you can still get there)! And don't stand up really quickly. It's worth chatting about with your GP to rule out any other possible reasons (a friend I knew once started fainting cos she had an undiagnosed kidney disease)! but I understand it's usually a pretty normal PG side effect!