Factor V Leiden and acquired activated protein C resistance among 1000 women with recurrent miscarriage

Activated protein C (APC) resistance, both in its congenital form, due to t he factor V Leiden mutation, and in its acquired form, are important risk f actors for systemic venous thrombosis. In view of the suspected thrombotic aetiology of some cases of recurrent miscarriage, the prevalence of APC res istance was determined among 1111 consecutive Caucasian women with a histor y of either recurrent early miscarriage (three or more consecutive pregnanc y losses at < 12 weeks gestation; n = 904) or a history of at least one lat e miscarriage (> 12 weeks gestation; n = 207). A control group of 150 parou s Caucasian women with no previous history of adverse pregnancy outcome was also studied. Acquired APC resistance was significantly more common among both women with recurrent early miscarriage (8.8%: 80/904; P = 0.02) and th ose with late miscarriage (8.7%: 18/207; P = 0.04) compared with controls ( 3.3%: 5/150), In contrast, the frequency of the factor V Leiden allele was similar among (i) women,vith recurrent early miscarriage (3.3%:60/1808; 58 heterozygotes and one homozygote), (ii) those with late miscarriage (3.9%:1 6/414; 14 heterozygotes and one homozygote) and (iii) the control group (4. 0%:12/300; 12 heterozygotes). Acquired but not congenital APC resistance (d ue to the factor V Leiden mutation) is associated with both early and late miscarriage.