I have always gotten pregnant with one try but did have a miscarriage with the first pregnancy. I was not diagnosed at the time and always wondered if it could have been linked to me not knowing I had crohns. But about 3 years later, while pregnant with my 2nd son, I stumbled across my medical records from the hospital visit due to the miscarriage. (My husband and I did not care to know the cause at the time) And I found that the baby had trisomy 9. I wish I could be of more help.
I know this really didn't help your question but wanted to let you know you are not alone.
Hang in there and I really hope everything works out for you.