Although alcohol does pass from a mother's blood to her breast milk, that doesn't mean she can't have a drink or two with dinner. Here's why:
If you have a drink, the concentration of alcohol in your breast milk is the same as the concentration of alcohol in your blood. But even if you were to drink to the point of legal intoxication (0.08 blood alcohol in most areas), your breast milk will still only contain the same amount of alcohol as your blood, so 0.08 percent. But that doesn't mean you're baby will have a 0.08 blood alcohol level.
This means your baby is only getting a tiny percentage of the alcohol you consumed. (Even non-alcoholic beer actually contains 0.6 percent alcohol–which is more than seven times the amount of alcohol that would appear in a mother's milk if she were legally drunk.)
Considering wine contains up to 12 percent alcohol, beer up to 5 percent, and hard liquor approximately 40 percent, the bottom line is that breast milk with an alcohol content of 0.08 is negligible and will not harm your baby. While you should avoid getting drunk for various reasons, most importantly so that you are capable of caring for your child, an occasional glass or two of wine is nothing to worry about.
Jack Newman, M.D. is one of North America's most respected breastfeeding experts. He is the author of Newman's Guide to Breastfeeding (Canada) and The Ultimate Breastfeeding Book of Answers (United States). Dr. Newman's breastfeeding information is available at www.drjacknewman.com