Prospective study of systemic lupus erythematosus pregnancies.

Different study designs have yielded different results on the effect of pregnancy on systemic lupus erythematosus (SLE) disease activity. Using the patient as her own control, and using nonpregnant SLE patients as controls, we have found flares to be more common in pregnancy. In SLE pregnancies followed prospectively at one center, we have found that preterm birth is the most frequent adverse event. Pregnancy loss occurred in 14%. Active SLE contributes to both preterm birth and to pregnancy loss. In addition, even in a first pregnancy, the presence of the lupus anticoagulant is associated with an increased risk of pregnancy loss.