Serum BAFF levels dip through mid and late pregnancy in women with lupus

Women with systemic lupus erythematosus (SLE) show a measurable dip in serum levels of B-Cell Activating Factor (BAFF) during the second and third trimesters of pregnancy, according to a longitudinal study published open access in Advances in Rheumatology on 28 September 2026. The finding, reported by Guilherme Ramires de Jesús and colleagues, comes from repeated blood sampling across five gestational windows in 167 pregnant patients with lupus, from whom 530 samples were analyzed.

BAFF is a cytokine that supports the survival of B cells, including autoreactive B cells that would otherwise be deleted, and its overexpression has been strongly linked to the pathogenesis of lupus.

The study enrolled three groups of pregnant women with SLE: 117 with inactive disease, defined as a Systemic Lupus Erythematosus Pregnancy Disease Activity Index (SLEPDAI) score below 4; 36 with active disease, defined as a SLEPDAI score of 4 or higher; and 14 with inactive SLE whose pregnancies were complicated by preeclampsia. Blood samples were collected at 14–18, 24–26, 30–32, 34–36 and 38–40 weeks of gestation, frozen at −80 °C, and later analyzed for BAFF concentrations. The researchers calculated medians and interquartile ranges and applied linear models with random effects to the longitudinal data.

Across all patients, mean serum BAFF declined from the 14–18 week window to the 24–26 and 30–32 week windows, and then rose again at 34–36 and 38–40 weeks. In the random-effects models, BAFF values were significantly lower at 24–26, 30–32 and 34–36 weeks compared with the values observed at 14–18 weeks. The authors concluded that pregnant patients with SLE had lower mean serum BAFF levels in the second and third trimesters compared with the end of the first trimester.

Notably, the trajectory of BAFF did not differ according to clinical status. When the three study groups were compared, there was no difference in BAFF levels, and the random-effects models found no difference in predicted values between patients with inactive and active SLE. Predicted BAFF levels in the preeclampsia group appeared slightly higher than in the other groups, but this difference did not reach statistical significance.

The study’s design carries both strengths and limitations worth noting. Sampling the same patient population repeatedly across pregnancy, rather than relying on single time points, allows within-person trajectories to be characterized, and the inclusion of separate groups for active disease and preeclampsia directly addresses questions that matter clinically for lupus pregnancies. At the same time, the preeclampsia group was small, with only 14 patients, which limits the precision of any estimate for that subgroup, and the authors themselves report that the slightly higher predicted values in that group were not statistically significant. The article was published as a peer-reviewed, accepted manuscript shared early with a permanent DOI, a version subject to further edits before the final Version of Record.

For clinicians and researchers, the results suggest that within the range of disease activity and pregnancy complications studied, serum BAFF followed a broadly similar gestational pattern regardless of SLE activity or preeclampsia status. The authors’ conclusions are deliberately scoped to this observation: lower mean levels in the second and third trimesters relative to the end of the first trimester, and similarity across the three patient groups.

Subject of Research: Longitudinal changes in serum BAFF levels during pregnancy in women with systemic lupus erythematosus

Article Title: Longitudinal analysis of serum B-Cell Activating Factor (BAFF) levels during pregnancy in women with systemic lupus erythematosus

Article References: Ramires de Jesús, G., Ramires de Jesús, N., Ignacchiti Lacerda, M., de Souza Nogueira, J., Calil Carneiro da Silva, R., Silva Freire Coutinho, E., Moreira de Sá, R. A., & Mendes Klumb, E. (2026). Longitudinal analysis of serum B-Cell Activating Factor (BAFF) levels during pregnancy in women with systemic lupus erythematosus. Advances in Rheumatology. https://doi.org/10.1186/s42358-026-00580-w

Image Credits: AI Generated

DOI: 10.1186/s42358-026-00580-w

Keywords: systemic lupus erythematosus, BAFF, pregnancy, preeclampsia, SLEPDAI, longitudinal study, cytokines, autoimmune disease, B cells, biomarkers, Longitudinal, analysis