Tulip, I don't see a problem with drinking a small amount of caffeine while you are pregnant - your body will tell you quickly enough if it doesn't agree with you! One of the main concerns is that caffeine interferes with iron absorbtion, so don't drink too much, but a cup here or there won't damage the baby.
I found that with all my pregnancies I had to cut out caffeine, I felt sick in the stomach if I had coffee and could only handle small amounts of tea. My tolerance levels changed throughout the pregnancy.

Kerrie