Managing nusinersen therapy during pregnancy in spinal muscular atrophy type 3

Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by SMN1 gene mutations. The introduction of disease-modifying therapies such as nusinersen has improved survival and functional outcomes allowing more patients to reach reproductive age. However, data on the safety of nusinersen use during pregnancy remain limited. Here, we report the first documented case in the USA of a woman with SMA type 3 who elected to discontinue nusinersen during pregnancy. Her pregnancy and delivery were uncomplicated, and she experienced mild functional decline with nusinersen therapy interruption that stabilised after postpartum resumption of therapy. This case aligns with prior international reports describing reversible clinical declines in motor function during treatment interruption. These findings highlight the importance of individualised, multidisciplinary care and underscore the need for prospective studies to guide reproductive counselling and therapy management in SMA.