Like Flowerchild said most of the time you don't get a reason. I was one of those. I don't know if I've given you my story before so I'll post it just in case I havent (if I have feel free to skip this post). After 3 years of trying in my marriage (10 years ago) I suffered an early loss - no reason found. Investigations with a leading IVF FS determined unexplained infertility. IVF recommended. My then husband was not interested at all in that process. We parted 5 years later (and never managed another pregnancy).

Fast forward to two years ago. My new DF and I decided to try for a baby. I felt I had no hope whatsoever as I was over 40 and I'd had no luck in my twenties and early 30's. Nine months later I was pregnant (early loss). I think it was 3 months later pregnant again (early loss again). No reason given for either loss - perhaps a small fibroid but more than likely it was just my age. Chromosonal testing found nothing. I was told IVF was my only chance of a successful pregnancy. After the 1st loss last year I was put on a waiting list for a fibroid resection and all the usual stuff they do with a lap before deciding if we should go the IVF route.

I was still waiting for it when I found myself pregnant for the third time in the year. I was off all my vitamins, drinking loads of coffee, drinking alcohol (in moderation), doing everything they tell you not to do when TTC. I was not actively TTCing when this pregnancy occurred. Despite the odds (supposedly about 5% for a successful unassisted pregnancy at age 42 at time of birth) this one stuck.

I guess what I'm saying is don't lose hope if the medical profession can't give you an answer. Miracles can and do happen. My little miracle came along when I least expected it.