Hi,
I here is some information for you, but the best thing to do is call your baby's physician when they open for any adverse effects to the baby. I don't think there would be....but better to call and be safe. Give you physician or dermatologist a call to in order to see how to care for you skin given the hormonal changes it is going through with breastfeeding....
Although micro derm abrasion is a great treatment for melasma (as is for any other pigmentation problem), you cannot have it until you deliver and finish breast feeding your baby.
Hormonal changes during pregnancy also make your skin more sensitive. At home microdermabration kits are not a good idea, because they might cause adverse reactions -- breakouts, irritations, blemishes, excessive dryness and itchiness. In-office treatments aren't safe for pregnant women either, because the skin may react adversely to before and after treatment products.
Moreover, hormonal changes also slow down the skin's recovery process. New skin cells take longer to form and reach the surface, allowing for scars and hypo pigmentation spots to appear on the treated skin.
Hope this helps some,
Julie