Safety and efficacy of continuous dimethyl fumarate treatment during conception, pregnancy, and lactation in females with multiple sclerosis: A case series

Background There is a delicate balance between managing the underlying disease and avoiding potential risks to the fetus in pregnant MS patients. This study aims to assess the impacts of continuing dimethyl fumarate (DMF) before, during, and after pregnancy in women with MS. Methods This retrospective study was conducted at an MS clinic in Isfahan, Iran, from August 2023 to March 2025. This study is part of a larger cohort of patients with relapsing-remitting MS who initiated treatment with DMF. Data were gathered in three categories: Disease, pregnancy, and infantile profile. Clinical and demographic properties of the patients, including EDSS scores, relapse rates, pregnancy and lactation complications, neonatal outcomes, and infantile development at six months postpartum, were collected. Results Twelve pregnancies were analyzed, resulting in 11 live births (91.7%), with 10 full‑term and one preterm delivery. One spontaneous abortion occurred at 22 weeks in a 38‑year‑old patient. Birth weights were within the normal range, and no congenital anomalies or developmental abnormalities were observed during the six‑month follow‑up. Maternal outcomes showed no relapses during pregnancy or postpartum, and EDSS remained stable. Pregnancy complications included gestational diabetes (n=2), hypertension (n=1), and anemia (n=1). Conclusion DMF may be relatively safe during conception, pregnancy, and lactation, and was associated with stable MS disease activity. However, further studies are required to confirm its safety profile.