Preventing Biologics from Crossing the Placenta During Pregnancy
Biologics have been a highly effective option to treat autoimmune diseases. However, some medications used to treat autoimmune diseases, like methotrexate and thalidomide, must be discontinued during pregnancy because of the exposure risk to the developing fetus. There is little evidence currently supporting the safe use of these therapies during pregnancy.
Normally, biologics can cross the placenta through the neonatal Fc receptor. In a recent study, scientists found that fusing IgG antibodies, which are the basis of many biologic drugs, to the protein albumin greatly reduced their transport across the placenta. The researchers demonstrated this in mouse models and in human placental tissue.
“By understanding this, we now have the opportunity to develop a new generation of biologic medicines that combine long-lasting efficacy with improved safety during pregnancy,” says Jan Terje Andersen, a professor at the University of Oslo and Oslo University Hospital who led the study.
If this approach enables biologics to be used more safely during pregnancy, it could help more people with autoimmune diseases continue treatment and manage symptoms while reducing fetal exposure.
Pregnancy and Autoimmune Disease
Pregnancy can pose unique challenges for people living with autoimmune disease. This series explores how immune changes throughout conception, pregnancy, and the postpartum period influence fertility, disease activity, treatment decisions, and maternal and infant health.
Citation
Nilsen J, Sand KMK, Al-Khabbaz HJ, et al. (2026) Fusion of IgG antibodies to albumin inhibits transport across the placenta. Sci Immunol. 11(122):eaee5151. https://doi.org/10.1126/sciimmunol.aee5151
