Recurrent miscarriage. II: Clinical associations, causes, and management.

Firm evidence on the causes of recurrent miscarriage is scant. The true rate is probably artificially heightened by a reproductive compensation effect. The commonest direct cause is probably repeated sporadic chromosome abnormalities, which occur consecutively merely by chance. Congenital and acquired anatomical defects of the uterine fundus and cervix, parental chromosomal rearrangements, gene mutations, antibodies to cardiolipin, and luteal phase defects each make a small contribution. Other causes, such as polycystic ovaries and immune rejection, may play some part but the evidence is not clear. Psychological stress, subclinical infections, thyroid disorders, and diabetes mellitus are probably not relevant. Reassurance and clear statements about prognosis are important and psychological support must be offered throughout investigation and subsequent pregnancy. Much more rigorous scientific studies from which clearer conclusions can be drawn are vital for better understanding of this important clinical problem.