As long as it's only ONE glass of wine (I think 6oz, maybe 8oz), especially reds because of their known heart health benefits, OR ONE (12oz beer), then it’s fine. It actually helps you to produce MORE milk, and to let down easier.
The only reasons I'd give you to stop post-hast would be if you are feeling Postpartum Depression, or you or your family have a history of alcohol dependency. If these reign as a factor, DO NOT continue! This behavior could lead to alcoholism if you have a history that leaves predisposed to the condition, and can sink you further into a depression if you’re already suffering. A good measure to know whether you’re beginning to become dependent on it is this: Do you think about when your next opportunity to have a drink is? If you are timing your day EVER by “your next drink”, you ARE addicted and should IMMEDIATELY seek help.
So long as depression and addiction aren’t issues to be concerned with, then ONE drink a day is fine. Just be sure that you’re honest with yourself and listen to your friends and family if they’re concerned. Alcoholics never believe that THEY have a problem. It’s always “that other guy” that has the problem, they are JUST FINE!
Hope it helps~ J.