Factor XII deficiency in women with recurrent miscarriage.

Congenital thrombophilia is known to cause significant maternal complications, and possibly has an adverse effect on normal fetal development. The aim of this study was to assess the prevalence of factor XII (FXII) deficiency in women with a history of recurrent miscarriage. Two hundred and forty-one consecutive Japanese women with a history of two or more recurrent miscarriages were prospectively assessed for their etiology by conventional screening methods. Seven women were found to have reduced FXII activity (19. 2-46.1%) and prolonged activated partial thromboplastin time (33. 3-51.3 s). Of these 7 women, 6 had experienced early pregnancy losses, while 1 woman had experienced repeated mid-trimester fetal losses with coincidental gestational thrombocytopenia. In 241 women with a history of recurrent miscarriage, the prevalence of FXII deficiency was 2.9%.