Reduction surgery may affect your ability to produce enough milk for your baby. This is usually due to ducts being severed during surgery and milk not having a way to exit from the nipple. There is no way of predicting what will happen when you try to breastfeed. You have to wait until the baby is born and see how it goes. One complication that may occur is when the milk "comes in" and your breasts get engorged, all the milk may not have a way to exit the nipples because the ducts were severed during the surgery or there may be scar tissue. Try to have the baby nurse and then pump after every nursing session to maximize the amount of milk you can get out. In a few days, the areas of the breast that had no exit will stop producing milk and your engorgement will decrease. The areas from which milk was removed will continue to produce and now you can work on increasing the production from those areas. See getting off to a good start and low milk production.