Thank you for your question. The numerical circumference measurement should not change after breast reduction. It is a good idea to let your surgeon know what your expectations are. Try not to focus too much on an exact size and more on the look that you are going for. As my college has stated finding a surgeon to give you an exact bra size will probably not happen. There are multiple reasons for this. Bra sizes are not standardized, size varies from maker to maker. Also your surgeon will do the best he/she can to give you the size your are looking for but in the end it is based on your body and the tissue your surgeon has to work with.
Best of luck,
Dr. Hisham Seify