Recurrent miscarriage: causes, evaluation and management.

Recurrent miscarriage is frustrating for the physician and a heartbreaking experience for the patient. Approximately 5% of couples trying to conceive have two consecutive miscarriages. Despite a thorough study of patients, the aetiology of this common obstetric complication is unknown in 50% of cases. Known causes include abnormal chromosomes, endocrinological disorders and uterine abnormalities. Although antiphospholipid antibodies have been demonstrated in miscarriages, the role played by alloimmune mechanisms remains unclear. New immunological approaches such as natural killer cells, regulatory T cells, tumour necrosis factor α, cell-derived microparticles, leptin, certain glycoproteins and cytokines should be considered. The management of thyroid diseases and immunological disorders is continuously evolving. Several genetic diagnostic procedures such as parental karyotyping and preimplantation genetic screening should probably not be used routinely. Antiphopholipid syndrome and some recurrent miscarriage-related endocrinological disorders can be effectively treated. Finally, new therapeutic approaches and the pleiotropic effects of old ones have led to improved fetal-maternal outcomes.