For some they will enlarge and stay that way, or they may enlarge while you are pregnant and breastfeeding but then return to your pre-pregnancy
size. That is what happened with me, they never stayed the same
size as when I was pregnant or nursing (unfortunately lol). That can cause your breasts to sag or have less volume, and if you paid a lot of money for an augmentation you might be unhappy with them after nursing if they do lose volume.