The effect of pregnancy on lupus nephritis.

OBJECTIVE: To evaluate the effect of pregnancy on lupus nephritis with respect to renal activity and renal deterioration.

METHODS: Seventy-eight pregnancies occurred in 53 women with systemic lupus erythematosus (SLE) and renal disease. Seventy-eight nonpregnant SLE patients with evidence of renal disease were matched to the study population by age at the time of each pregnancy and by the presence of a renal manifestation at the beginning of the study. The nonpregnant controls were seen within 2 years of the assessment dates of the pregnant patients with whom they were matched. Renal activity was defined as the presence of active urine sediment or proteinuria, and changes in these parameters were monitored throughout the study period in both study populations. Renal deterioration was defined as an increase in the serum creatinine level that was >20% above the baseline value or an increase to >120 mmoles/liter.

RESULTS: Renal disease activity patterns were available for 74 pairs of pregnancies and controls. Renal disease became active during the study period in 33 pregnancies (44.6%) and 31 controls (41.9%). Serial serum creatinine levels were available for 75 study pairs, among which 62 pregnancies (82.7%) and 57 controls (76.0%) showed no deterioration. Comparison of the treatments received by both the pregnant and the nonpregnant patients showed no significant difference in the amount of steroids taken. A significantly lower amount of immunosuppressive and antimalarial agents were taken during the pregnancies.

CONCLUSION: During pregnancy in patients with SLE and renal disease, changes in renal disease activity and deterioration in renal function are similar to those which occur in nonpregnant patients with lupus nephritis.