I believe it's different for everyone with some I lost size and with others I stayed the same. I breastfed a few and formula others. First kid in 2000 I went from full C to a decent B by the time 2004 kid came around I was a DD and dropped all the way to a B I started at a large B with this baby but I'm still breastfeeding and I shit you not some days I feel like the suckeres are gonna get up and run away they have their own zip codes in the form of F cups. Your tissue does not change as far as I'm aware but the stretch and shrink of your milk glands can fluctuate.