ADHD and Post Partum/hormones?

My wifes ADHD symptoms seem to have DRAMATICALLY increased just after the birth of our child (he is now 11).  Post partum depression was why we sought a counselor and she was diagnosed...she obviously had had it all along, but since then it seems to have gotten worse. Is that logical? Of course,it COULD just be that the daily rigors of caring for a child, im sure that has something to do with it, but Im wondering if it might be more than that...perhaps related to hormonal changes.  any clinical relationship between the two?