I think caffeine stays in the breastmilk for some time- as in, not rapidly processed (can't think of the word!!). It can cause jitters in babies, sleeplessness, increased heart rate etc as with the effects it has on adults. Personally I don't think that it is worth drinking it. Like BB said, try Madura tea, Virgin Garden (if you can find it) or my very favourite Vital Organics Rooibos tea (avail in Woolworths). The rooibos tea is yummy (after your 2nd cup- I didn't like the first one) and is naturally caffeine free. If you really need the coffee, why not get a decaf one and for the first few days mix it half and half with your normal one till you go to full decaf?