RESUMEN
The impact of pregnancy and breastfeeding on the development and outcomes of Multiple sclerosis (MS) has been debated for decades. Since several factors can influence the evolution of the disease, the protective role of multiparity and breastfeeding remains uncertain, as well the role of hormone replacement therapy in the perimenopausal period. We report two cases of relatively late-onset MS in two parous women, who developed their first neurological symptoms after six and nine pregnancies, respectively. Both women breastfed each of their children for 3 to 12 months. One of them underwent surgical menopause and received hormone replacement therapy for 7 years before MS onset. We performed a systematic literature review to highlight the characteristics shared by women who develop the disease in similar conditions, after unique hormonal imbalances, and to collect promising evidence on this controversial issue. Several studies suggest that the beneficial effects of pregnancy and breastfeeding on MS onset and disability accumulation may only be realized when several pregnancies occur. However, these data on pregnancy and breastfeeding and their long-term benefits on MS outcomes suffer from the possibility of reverse causality, as women with milder impairment might choose to become pregnant more readily than those with a higher level of disability. Thus, the hypothesis that multiparity might have a protective role on MS outcomes needs to be tested in larger prospective cohort studies of neo-diagnosed women, evaluating both clinical and radiological features at presentation.