Antiphospholipid antibodies and preeclampsia: A case-control study

Objective: To assess the association between the occurrence first of preeclampsia and antiphospholipid antibodies. Methods: We conducted a prospective case-control study of 180 pregnant women with their first incidents of preeclampsia and no histories of thrombosis or systemic autoimmune diseases. Preeclampsia (n = 180) was defined as blood pressure (BP) at least 140/90 mmHg after 20 weeks' gestation and proteinuria at least 0.3 g per 24 hours. Two control subjects were matched to each case (n = 360). They were pregnant women without hypertension or proteinuria and without histories of thrombosis or systemic autoimmune disease. Lupus anticoagulant (activated partial thromboplastin time, diluted thromboplastin time, platelet neutralization procedure) and anticardiolipin antibodies (immunoenzymatic assays) were assessed in both groups, and the coagulation state (levels of thrombin-antithrombin III complexes, fragments 1 + 2 of prothrombin) was also evaluated. The analysis design was a sequential plan with 5% type I error and 95% power. Results: There was no association between antiphospholipid antibodies and preeclampsia. The odds ratio for the association was 0.95 (95% confidence interval 0.45, 2.61). Antiphospholipid antibodies were detected in eight of 180 preeclamptic women and in 19 of 360 controls. In contrast, there was a clear, confirmed activation of coagulation during preeclampsia. Conclusion: Despite evidence of a prothrombotic state during preeclampsia, it is unlikely that antiphospholipid antibodies (lupus anticoagulant and anticardiolipin anti-bodies) represent risk factors for preeclampsia among women with no previous preeclampsia and no histories of thrombosis or systemic autoimmune disease. (Obstet Gynecol 2001;97:29-34. (C) 2001 by The American College of Obstetricians and Gynecologists.)