Effects of Pregnancy and Breastfeeding on Clinical Outcomes and MRI Measurements of Women with Multiple Sclerosis: An Exploratory Real-World Cohort Study

Introduction Pregnancy represents an important event for women with multiple sclerosis (MS) and is often accompanied by post-partum disease reactivation. To date, the influence of this reproductive phase on long-term MS outcomes is still largely unexplored. The objective of the study was characterise a large real-world cohort of women with MS to evaluate the effects of pregnancy and breastfeeding on short- and long-term clinical and magnetic resonance imaging (MRI) outcomes while exploring the relationships with MRI measurements of brain atrophy. Methods MS patients with and without pregnancy were recruited. Clinical relapses and MRI activity of the year before conception versus the year after delivery were evaluated. Regression models were performed to investigate the relationships between long-term MS outcomes (EDSS score and MRI brain measurements obtained by SIENAX software) and pregnancy and breastfeeding duration. Results Two hundred ten women with MS were enrolled; of them, 129 (61.4%) had at least one pregnancy. Of all pregnancies (n = 212), those that occurred after MS onset (90 [42.4%]) were examined to evaluate the short-term outcomes. A higher annualised relapse rate in the post-partum year versus the pre-conception year (0.54 +/- 0.84 vs. 0.45 +/- 0.71; p = 0.04) was observed. A regression analysis showed that clinical activity after delivery was associated with clinical activity of the year before conception (p = 0.001) as well as duration of breastfeeding (p = 0.022). Similarly, post-partum MRI activity was associated with pre-conception MRI activity (p = 0.026) and shorter breastfeeding duration (p = 0.013). Regarding long-term outcomes, having had at least one pregnancy during MS was associated with a lower EDSS score (p = 0.021), while no relationships were reported with MRI measurements. Conversely, a breastfeeding duration > 6 months was associated with lower white matter volume (p = 0.008). Conclusions Our study underlines the importance of considering the effects of pregnancy and breastfeeding on short- and long-term MS outcomes. In the current therapeutic landscape, pregnancy planning and treatment optimisation in the post-partum period, in particular for women who choose to breastfeed, are fundamental for the management of these biological phases so central in a woman's life.