Exact location of abdominal pain is important fact for suspecting certain cause.
Since you have related this pain with miscarriages you had, I assume you are thinking about lower abdominal pain.
There are different causes for this type of pain like uterine fibroids, ovarian cysts, endometriosis, bladder infection, UTI's, diverticulitis, and other conditions.
Pain in the lower abdomen can also be caused by problems arising from the back.

Best wishes!