I have no *real* answer for you...only my thoughts based on my own experience. I haven't found any research to support this, but it is my belief that there is a brief "window" for some of us who deal with IF due to hormone stuff. After you give birth and while you are nursing, your hormones are wonky naturally, but perhaps this time of crazy hormones makes us closer to what our hormones should be. Does that make any sense? I have heard of many women who had trouble ttc the first and had an easier time with the second, but that could also be due to other stuff too (knowing how to temp., check for signs of o, etc.).
According to my theory, my daughter was a result of that "window". Now ttc a third, we have obviously missed the window and are stuck in IF land once again with similar issues that we faced with ttc our first.
I'm curious to see what others say. In any case, best wishes and good luck!!
Mom to ds (7/02), dd(2/04), ds (9/07), and dd 9/09