Serum BAFF levels in pregnant patients with systemic lupus erythematosus

Background/PurposeThe B cell Activating Factor (BAFF) signaling pathway influences rheumatic disease through its role in the selection, maturation, and survival of B cells. Increased BAFF also correlates with hypertension and preeclampsia in pregnant women without rheumatic disease. We sought to correlate BAFF levels in pregnancy with pregnancy outcomes among women with rheumatic disease.MethodsBlood samples, disease activity assessments, labs, and pregnancy outcomes were prospectively collected from pregnant women with systemic lupus erythematosus (SLE). Inclusion criteria were enrollment prior to 30 weeks gestation and known pregnancy outcome. Preeclampsia diagnosis was determined through chart review and consensus among 6 providers (maternal-fetal medicine, nephrology, and rheumatology); pregnancies were excluded if a preeclampsia diagnosis could not be agreed upon. We assessed for changes in BAFF levels throughout pregnancy, and we investigated its association with disease activity and adverse pregnancy outcomes.ResultsThis study included 408 samples in 230 women with SLE (<i>n</i> = 110) and other rheumatic diseases (<i>n</i> = 120). The average maternal age was 31.3 years and self-reported race was 5% Asian, 30% Black, and 61% White. The median level of BAFF was significantly higher in the 1st trimester compared to the 2nd and 3rd trimester measures (<i>p</i> = .002). Among women with SLE, compared to pregnancies without preeclampsia, those with preeclampsia had significantly higher BAFF levels in the first trimester (2061 vs 1217 pg/mL, <i>p</i> = .007). In models adjusted for age, obesity, and maternal race, patients with SLE experienced a 19% higher odds of developing preeclampsia with every 100-unit increase BAFF in the first trimester (AOR 1.19; 95% CI: 1.05, 1.36). Women with SLE and elevated BAFF levels were more likely to have elevated dsDNA, but not more likely to experience lupus nephritis during pregnancy.ConclusionThis study found elevated BAFF levels in the first trimester of pregnancy were associated with subsequent development of preeclampsia. While elevated BAFF was associated with elevated dsDNA, it was not associated with lupus nephritis, the strongest predictor of preeclampsia among women with SLE. This finding suggests that elevated BAFF early in pregnancy may be a novel risk factor for poor pregnancy outcomes in women with SLE.