Immunomodulatory agents and risk of postpartum multiple sclerosis relapses.

OBJECTIVE To determine whether treatment with an interferon beta or glatiramer acetate shortly after delivery reduces the otherwise increased risk of postpartum relapses of multiple sclerosis. METHODS In a retrospective cohort of 112 women with multiple sclerosis and live births from Kaiser Permanente Southern California, complete medical and pharmacy records of the mothers and infants were reviewed. Propensity score-adjusted hazard ratios (HR) of time to first postpartum relapse were calculated. RESULTS Of 80 women who breastfed little or not at all, 55 (69%) resumed treatment within 1 year postpartum, of whom 26 (47%) relapsed within 6 months postpartum. Resuming treatment within 2 weeks postpartum did not decrease the risk of relapse in the 2 years postpartum compared with women who resumed treatment later in the postpartum year (propensity score-adjusted HR = 1.3, 95% confidence interval = 0.5-3.4, p = 0.6). There was no difference in relapse rates between the groups in the first 6 months postpartum. However, later in the postpartum year those who resumed treatment early had fewer relapses (p = 0.08, Poisson regression). CONCLUSIONS Among women who breastfeed little or not at all, starting treatment with interferon beta or glatiramer acetate within two weeks postpartum does not reduce the risk of postpartum relapse of multiple sclerosis but may reduce the risk of subsequent relapses in the postpartum year.