Monoclonal Antibody Dispensing Around Pregnancy: A Descriptive Analysis Using Electronic Health Records in Italy

This is the authors' abstract. We don't add key points for this paper.

PURPOSE: To describe trends in dispensing of monoclonal antibody biologics (mAbs) for autoimmune conditions during and around pregnancy. METHODS: We conducted a population-wide study of women of reproductive age (14-49 years) resident in Lombardy, Italy, between 2012 and 2024. We described trends over time in the prevalence of mAb dispensations among women of reproductive age, and during pregnancy. For each pregnancy, we assessed the prevalence of mAb dispensations before, during, and after pregnancy in trimesters. We described dispensing patterns and explored maternal factors associated with discontinuation. RESULTS: We included 1 871 929 women of reproductive age and 855 865 pregnancies. Prevalence of mAb dispensing during pregnancy increased over 60-fold over the study period, from 0.0041% in 2012 to 0.27% in 2024. Pregnancy affected mAb dispensing, with prevalence decreasing from 0.081% before pregnancy to 0.051% by the third trimester. Over half (n = 385/722, 53.3%) of pre-existing mAb users discontinued before or during pregnancy, while switching between mAbs during pregnancy was rare (n = 24/722, 3.3%). Discontinuation decreased over time, and varied substantially between mAbs. We found limited evidence that sociodemographic factors were associated with discontinuation, but that some health factors may be, such as use of assisted reproductive technology (OR = 1.92, 95% CI: 0.98-3.77). CONCLUSIONS: Italian population-wide data from 2012 to 2024 show an increase in mAbs dispensed during pregnancy, and fewer instances of discontinuing these drugs over time. These trends may reflect increasing drug availability, accumulating safety evidence, and recent changes in guidelines for mAb use in pregnancy. People with autoimmune conditions who experience moderate or severe symptoms are often treated using monoclonal antibody drugs, which may also be called biologics. There are some concerns around whether these drugs are safe to use during pregnancy because there is limited and emerging data on how they affect maternal and neonatal complications. We studied women of reproductive age in Lombardy, Italy, between 2012 and 2024. Our aim was to describe trends in how monoclonal antibodies are dispensed around pregnancy. We found that over this period the use of these drugs increased substantially in women of reproductive age and during pregnancy. Around half of women stopped using monoclonal antibodies just before or during their pregnancy, though this varied between drugs. Stopping during pregnancy was also more likely if a pregnancy was conceived using fertility treatments such as in vitro fertilisation (IVF). Switching between monoclonal antibodies during pregnancy only occurred in around one in 30 pregnancies. In more recent years, women were more likely to continue using monoclonal antibodies throughout pregnancy. This trend fits with recent recommendations from medical organisations and may be influenced by new safety data, changes in symptom severity among women, or increasing availability of these drugs.