Pregnancy does not cause systemic lupus erythematosus to worsen.

To evaluate risk for exacerbation of systemic lupus erythematosus (SLE) during pregnancy, we prospectively evaluated 80 pregnant women with SLE for manifestations of disease activity. Fifty-three of these women were not taking prednisone at the time of conception. Disease activity was scored in 4 ways: global assessment, prednisone therapy, cumulative number of organ systems with abnormalities, and display of abnormalities of each organ system. No patient received prophylactic therapy to prevent disease exacerbation. Thrombocytopenia, proteinuria, and hypocomplementemia were the most common abnormalities and were usually attributable to the pregnancy complications of preeclampsia and anticardiolipin antibody syndrome rather than to SLE. If all possible abnormalities were attributed to SLE, disease exacerbation occurred in less than 25% of all patients; if only SLE-specific abnormalities were counted, disease exacerbation occurred in less than 13%. Worsening of SLE is uncommon in pregnancy, and prophylactic prednisone therapy is unnecessary.