bras after delivery

So my boobs have not grown one bit so I hadn't thought of needing new bras but a friend told me today that after the baby comes they will get much bigger. I said maybe I would just pick up a couple sports bras since I don't know how big I will get and surely won't be rushing out shopping and she said that these will decrease milk production... Is this true?! Anyone heard of that or should I just go get some sports bras?!