Abortion is the expulsion of products of conception either fully or partially.
The causes of abortion vary from hormonal disturbances any trauma or injury, a severe shock, infectious and foetal abnormalities. It is a nature's way of rejecting a malformed baby.
Other reasons can be:
Uterine weakness or displacement.
Cervical canal weakness.
Bleeding from vagina either profuse or in spots.
Pain is usually the dull type of pain in abdomen and back.