Don't avoid eating it. It's actually meant to be good for you when pregnant.

I came across some research somewhere while I was pregnant that found that women who eat chocolate 5 or more times a week while pregnant are less likely to get pre eclampsia.

A friend of mine who normally ate chocolate every day couldn't stand it whilst pregnant and ended up with pre eclampsia. I ate it pretty much every day and didn't get it even though I was considered to be at a higher risk of getting it because of being a first time mum over the age of 40.

I say go for it.