Factor XII (Hageman) deficiency in women with habitual abortion: new subpopulation of recurrent aborters?

To examine the possible association between factor XII (FXII) deficiency and an elevated number of abortions.

Factor XII activity, FXII antigen concentration, other blood clotting parameters, and phospholipid antibodies were examined in venous blood from 43 women with repeated (3 to 7) abortions before the 28th week of gestation but without gynecological and chromosomal abnormalities. The data were compared with those obtained from 49 age-matched women without fetal loss.

Eight cases with moderately reduced FXII activity (35% to 68% of normal) could be identified in the abortion group, whereas among controls no abnormalities in FXII activity and antigen concentration were found. The relative occurrence of reduced FXII level was higher among patients with more than three abortions as compared with those with three abortions.

Repeated abortions may be associated with reduced level of FXII activity of unknown origin.