I think they say to try and time it so there is the longest amount of time possible between having a drink and a feed. I've actually heard it's best to drink while feeding (what a sight).
I have a glass of wine on a Fri or Sat night sometimes and last night (first on hols in Cornwall) I had a real ale shandy (I know, those words should never be seen together)!
Some people will say a big no, but I say if I do limit it I'm happy to.