Early Leukocyte Profiles in Preterm Infants Born to Mothers with Systemic Lupus Erythematosus: An Exploratory Matched...

Background/Objectives: Maternal systemic lupus erythematosus (SLE) is associated with preterm birth, but whether maternal disease activity influences early neonatal hematologic profiles beyond developmental immaturity remains unclear. We compared hematologic parameters between SLE-exposed preterm infants and maturity-matched controls and explored findings according to maternal SLE flare during pregnancy. Methods: This single-center retrospective matched-cohort study included 13 SLE-exposed preterm infants and 39 controls matched 1:3 by gestational age, birth weight, and sex. White blood cell (WBC) count, absolute neutrophil count (ANC), hemoglobin concentration, and platelet count were assessed at birth, around postnatal day 5, and at their nadir during hospitalization. Group differences were estimated using linear regression models including matched-set identifiers as fixed effects. Flare-stratified and hepatic analyses were exploratory, without adjustment for multiple comparisons. Results: Overall matched-set analyses showed no clear differences in WBC count, ANC, hemoglobin, or platelet values between SLE-exposed infants and controls. The estimated difference in nadir ANC was -405/μL (95% confidence interval [CI], -985 to 174/μL; p = 0.164). In the maternal-flare subgroup, nadir WBC count was lower than in its matched controls (difference, -2.31 × 10³/μL; 95% CI, -3.96 to -0.65 × 10³/μL; p = 0.009), as was nadir ANC (difference, -672/μL; 95% CI, -1260 to -85/μL; p = 0.028). Corresponding matched-set differences were not evident at birth or around postnatal day 5. The non-flare subgroup did not show a consistent pattern of leukocyte suppression. Conclusions: Maternal SLE exposure was not clearly associated with an overall difference in neonatal hematologic profiles within matched sets. Maternal SLE flare may identify a subgroup with lower WBC and neutrophil nadirs, but this exploratory finding requires confirmation in larger studies.