When I found out I was pregnant, I gave up drinking and smoking. I gained quite a bit of weight during my pregnancy, but I figured I'd be gaining weight anyway. LOL.
Edit to add: I do think the very best thing you can do is be honest with your doctor and let him/her know about your drinking. While detoxing may be quite uncomfortable for a few days, I do think not drinking would be the very best thing while you are pregnant.