Antiphospholipid antibodies and recurrent abortion.

We examined the association between anticardiolipin antibodies, lupus anticoagulant, and the risk of recurrent spontaneous abortion in a case-control study conducted in a network of general and teaching hospitals in northern Italy. Subjects consisted of 220 women with two or more unexplained consecutive spontaneous abortions and 193 controls admitted for acute conditions other than immunologic, infective, gynecologic, or cardiovascular. Lupus anticoagulant was detected in 16 of 220 cases (7%, 95% confidence interval 4-11%) but in none of the 193 controls (Fisher exact test, P less than .001). Increased anticardiolipin antibody levels were demonstrated in 19 of 99 cases (19%, 95% confidence interval 12-31%) (seven immunoglobulin (Ig) G, eight IgM, and four IgG and IgM) and in four (all IgG) of 157 controls (3%) for whom data were available. These results offer quantitative evidence on the association between antiphospholipid antibodies and recurrent abortion.