You're not alone ArgieMom, a lot of us breastfed with the mirena, not knowing it's not recommended for breast feeding moms. There's enough studies done to show the hormones are passed on to the baby, but not enough to show definitely that there's any harm done, or that it's safe. If your son seems healthy, don't worry yourself sick over it, just mention it at your son's next check-up, see what the pediatrician has to say.