I realize this thread was bumped up recently, but the original post is from 2008. Whatever they have, and it would be great if they updated, it's likely been resolved by now. :)
Sounds like you have herpes. It can lie dormant until physical or emotional stressful situations-pregnancy is definitely one of them. I would have your wife get checked out for sure since she’s pregnant. You can get herpes on other places than your genitals.
I concur with the previous answer posted. However, if the tests come back negative for herpes you might consider your personal care and cleaning products (bath soap, laundry soap, scented sprays, deodorants, etc.) have you been using something new? Even sexual lubricants can cause allergic symptoms. Just a thought.
Your wife should get this checked out as soon as possible since she is 37 weeks pregnant.
You both should be tested for herpes, and her sores can be cultured, and should be.
Whenever you have strange symptoms, you should get it checked out.