Passive maternal immunity in children born to women with systemic autoimmune rheumatic disease - A case-control study

The transplacental transfer of maternal antibodies is essential for neonatal immunity but can be affected by maternal health conditions and pregnancy complications. In women with systemic autoimmune rheumatic diseases (SARD) this transfer may be influenced by the autoimmune condition itself and/or the immunosuppressive therapies administered during pregnancy.

This study aimed to assess the transplacental transfer and efficacy of vaccine-induced antibodies in pregnant women with SARD compared to healthy controls.

We enrolled pregnant women with and without SARD pregnancy. Venous blood samples were collected during the third trimester, and umbilical cord blood was obtained postpartum. Antibody titers were assessed using Roche SARS-CoV-2 RBD ECLIA for SARS-CoV-2 and DiaSorin kits for varicella-zoster virus and rubella.

25 pregnant women with SARD and 30 healthy controls were analyzed. Of these, 25 women were vaccinated against SARS- CoV-2 during pregnancy. Transplacental antibody transfer was effective in the SARD and in the control groups. Rubella and SARS-CoV-2 antibody levels showed no significant differences in either maternal or cord blood samples. Varicella-zoster virus antibody levels were higher in SARD maternal and cord sera than in controls. In all cases maternal and neonatal antibody titers were highly correlated (p < 0.001).

Our findings suggest effective maternal-to-fetal antibody transfer in women with SARD both for existing antibodies (varicella-zoster virus, rubella) as well as newly generated ones (anti-Covid Igs generated after vaccination during pregnancy), indicating robust passive immunity in their newborns.