Causes of recurrent abortion

Uterine defects (congenital anomalies, submucous and intramural leiomyomas, polyps, intrauterine adhesions)
Cervical incompetence
Infections
Endocrine causes (luteal phase defects, polycystic ovary disease, thyroid abnormalities, diabetes)
Chromosomal abnormalities (translocations, inversions)
Severe maternal illness (Wilson's disease, maternal phenylketonuria, cyanotic heart disease, hematologic disorders [hemoglobinopathies or aplastic anemia], inflammatory bowel disease, neoplasia)
Autoimmune disease, antiphospholipid syndrome
Thrombophilic defects
Alloimmune disease (shared parental histocompatibility)
Chemicals, X-rays, and other noxious agents
Psychological factors