Transplacental transfer of ravulizumab in a pregnant woman with neuromyelitis optica: a case report.

Neuromyelitis optica spectrum disorder (NMOSD) is a rare relapsing autoimmune disease of the central nervous system (CNS). Management during pregnancy is challenging due to limited safety data for disease-modifying therapies. We report a case of a 41-year-old woman with aquaporin-4 (AQP4) IgG positive NMOSD who was switched from rituximab to ravulizumab during pregnancy. Ravulizumab was initiated shortly after conception and continued throughout pregnancy. Pregnancy was uneventful and she delivered a healthy term infant. At birth, umbilical cord blood testing revealed detectable ravulizumab levels and low C5 activity, confirming transplacental transfer of ravulizumab. The infant, now 4 months old, remains well. This is the first reported case of ravulizumab use during pregnancy, with documentation of transplacental drug transfer and neonatal complement inhibition. Despite laboratory evidence of pharmacologic exposure, the neonate remained clinically well. These findings suggest that ravulizumab may be a viable treatment option for NMOSD during pregnancy when traditional agents are contraindicated or ineffective. However, further studies and longitudinal monitoring of exposed infants are essential to establish safety and clinical guidelines.