A case series of rheumatoid arthritis patients exposed to an etanercept biosimilar during pregnancy: Evidence from an increasingly accepted treatment option

OBJECTIVE: To assess pregnancy and neonatal outcomes in women with rheumatoid arthritis treated with an etanercept biosimilar, and to provide real-world safety evidence. METHODS: This retrospective, single-centre study included 11 pregnant women with rheumatoid arthritis who received an etanercept biosimilar at the National Center for Child Health and Development (Tokyo) between October 2018 and March 2022. The clinical characteristics, disease activity, medications, delivery outcomes, and neonatal health were reviewed. RESULTS: All 11 pregnancies were live births. The median maternal age was 34 years, the gestational age at delivery was 39.7 weeks, and the birth weight was 2929 g. One preterm birth (9.1%) and two caesarean deliveries (18.2%) occurred. No cases of low birth weight or neonatal intensive care unit admission were reported. One case of patent foramen ovale was noted. All neonates had 5-minute Apgar scores of ≥9. The etanercept biosimilar was discontinued before delivery in four cases to allow for infant vaccination. CONCLUSION: Use of the etanercept biosimilar during pregnancy was associated with favourable outcomes, supporting its safety and utility in managing rheumatoid arthritis during pregnancy.