Maternal and neonatal outcomes following natalizumab use during pregnancy in women with multiple sclerosis: A multicenter observational study

INTRODUCTION: Pregnancy in multiple sclerosis (MS) is associated with reduced relapse activity, though the postpartum period carries a heightened risk of disease reactivation. Continuation of natalizumab late gestation has been proposed to mitigate this rebound effect and maintain disease stability. METHODS: This retrospective study included 62 women with MS with initial pregnancy plans. Of those 32 continued natalizumab infusion until the 34th week of gestation and 30 discontinued natalizumab treatment upon confirmation of pregnancy. Participants were assessed pre- and within three months postpartum for disability status (EDSS), relapse occurrence, and MRI activity (presence of gadolinium-enhancing [GdE + ] lesions). Neonatal anthropometric parameters (birth weight, length, head circumference) were also recorded. RESULTS: Within the natalizumab group, outcomes improved from baseline (last preconception assessment) to the postpartum follow-up (≤3 months after delivery) with lower EDSS scores (p = 0.003), marked reductions in relapse frequency and GdE + lesions (p < 0.001 for both). The non-natalizumab group showed smaller reductions in relapse rates and no significant change in MRI activity. Between-group comparisons at postpartum follow-up revealed lower EDSS scores (p = 0.028), fewer relapses (p = 0.029), and fewer GdE + lesions (p = 0.001) in the natalizumab group. Neonatal anthropometric parameters did not differ significantly between groups and WHO Child Growth Standards (p > 0.05). CONCLUSIONS: Continuing natalizumab treatment until late pregnancy was associated with better postpartum clinical and radiological outcomes. Neonatal anthropometric measures were comparable to reference child growth standards. These findings support that late pregnancy natalizumab continuation may be a viable high efficacy strategy for women with highly active MS.