Outcome of pregnancy in patients with systemic lupus erythematosus. A prospective study. A prospective study was performed to investigate the outcome and complications of pregnancy in patients with systemic lupus erythematosus. Twenty-nine pregnancies occurred in 22 patients. There were 12 abortions, two spontaneous and 10 induced. Fifteen women had 17 live-born neonates. Neonatal complications included nine premature deliveries, two cases of intrauterine growth retardation, and one of Treacher Collins syndrome. Obstetric complications included threatened abortion (two), placenta previa (two), and preeclampsia (three). Cesarean sections were necessary in five patients. There was no maternal or neonatal mortality. Thirteen episodes of systemic lupus erythematosus relapses were detected by incidents of increasing proteinuria (six), arthritis (four), and vasculitic rash (two). There were no statistical differences in changes in hemoglobin level, erythrocyte sedimentation rate, albumin level, antinuclear antibody titer, or C3 or C4 level between the patients who relapsed and those who did not. Pregnancy could induce a flare of systemic lupus erythematosus in previously normal patients or patients with previously inactive disease. The overall neonatal and maternal survival was good, even in patients who presented during pregnancy. Spontaneous fetal loss was low (2/29 [6.9%]); both cases occurred in mothers with inactive lupus. 