Maternal and fetal complications in pregnant women with systemic lupus erythematosus. Recent studies provide important insights into maternal complications in patients with systemic lupus erythematosus (SLE) established before onset of pregnancy. Exacerbations or relapse occur during the course of pregnancy and immediately postpartum in 25% to 60% of pregnancies. However, the likelihood of increased clinical activity of SLE during pregnancy is influenced by signs of activity present at onset of pregnancy. In the absence of signs of clinical activity for at least 6 months before conception, relapses occur in about one third, whereas in patients with clinical activity at onset of pregnancy, persistent activity or exacerbations occur in approximately two thirds. Fetal survival in these patients parallels the incidence of SLE activity: 85% to 95% in the group with inactive disease at conception and 50% to 80% in subjects with active disease at onset of pregnancy. The introduction of an assay for anticardiolipids has led to a new concept for the pathogenesis of autoimmune disease, namely immune-related thrombosis. Recent studies suggest that this mechanism may play an important role in clinical episodes in SLE, involving late fetal death and maternal arterial and venous thrombosis. 