L.D.
Not the answer to your question, but I am wondering why you and your ob/gyn choose the IUD for birth control. If you look at the website or see the commericials for IUD's like Mirania the first qriteria is a monagamous relationship, which the serial monogamy does not fall under. You may fall into this safe zone but you partner may not. The string habors bacteria and infection.
Anyway to my knowledge the IUD does not contain any hormones so wt gain shouldnt be a side effect, right. Ithink portion size is a big part of my wt, so I have started using small plates and not going back for seconds. Also have added fruit which really is good and good for you.
Good luck and enjoy your daughter they grow way to fast.