Plasma interferon-alpha protein levels during pregnancy are associated with lower birth weight in systemic lupus erythematosus

Objectives Adverse pregnancy outcomes are more common in women with SLE compared with healthy women, but we lack prognostic biomarkers. Plasma IFN-alpha protein levels are elevated in a subgroup of pregnant women with SLE, but whether this is associated with pregnancy outcomes is unknown. We investigated the relationship between IFN-alpha, adverse pregnancy outcomes and the presence of autoantibodies in SLE pregnancy.Methods We followed 76 women with SLE prospectively. Protein levels of IFN-alpha were quantified in plasma collected in the second and third trimester with single-molecule array. Positivity for ANA and aPL antibodies was assessed during late pregnancy with multiplexed bead assay. Clinical outcomes included the adverse pregnancy outcomes small for gestational age (SGA), preterm birth and preeclampsia.Results During SLE pregnancy, women with SGA infants compared with those without had higher levels of plasma IFN-alpha protein, and IFN-alpha positivity was associated with lower birth weight of the infant. Preterm birth was associated with autoantibodies against chromatin. IFN-alpha protein levels associated positively with autoantibodies against chromatin, Smith/RNP (SmRNP) and RNP, but negatively with aPL antibodies.Conclusion Elevated IFN-alpha protein in plasma of women with SLE is a potential risk factor for lower birth weight of their infants. The association between IFN-alpha and lower birth weight warrants further investigation regarding the pathophysiological role of IFN-alpha during SLE pregnancy. Graphical Abstract