Fertility does not seem to be impaired to a larger extent in women with MS. However, infertility and MS might just come coincidentally together and, therefore, MS patients might undergo assisted reproductive treatment (ART). Thus, during the last years different studies evaluating the effects of ART on MS relapses have been published. All of them reported an increase in annualized relapse rate after ART. Furthermore, in a recent study clinical worsening was associated with an increase in MRI activity. Putative mechanisms involved in MS worsening after ART include: temporary interruption of disease modified therapies, stressful events associated with infertility, and immunological changes induced by hormones such as increase in pro-inflammatory cytokines and anti-MOG antibodies, as well as an increase in immune cell migration across the blood-brain-barrier. Overall, neurologists should be aware of this risk and discuss the pros and cons of the procedures with MS patients.