Fertility, pregnancy and childbirth in women with multiple sclerosis: a population-based study from 2018 to 2020

Background: We aim to evaluate whether fertility, pregnancy, delivery and breastfeeding have been actually improving in women with multiple sclerosis (MS), compared with general population, and in relation to treatment features. Methods: We included 2018-2020 population-level healthcare data on women with MS living in the Campania region (Italy). Fertility, pregnancy and delivery outcomes were obtained from Certificate of Delivery Assistance; breastfeeding was collected up to 6 months after delivery by trained personnel. Results: Out of 2748 women with MS in childbearing age, 151 women delivered 156 babies. Fertility rate was 0.58 live births per woman with MS, compared with 1.29 in Campania region and 1.25 in Italy. Disease-modifying treatment (DMT) continuation during pregnancy was associated with lower birth weight (coeff -107.09; 95% CI -207.91 to -6.26; p=0.03). Exposure to DMTs with unknown/negative effects on pregnancy was associated with birth defects (OR 8.88; 95% CI 1.35 to 58.41; p=0.02). Birth defects occurred in pregnancies exposed to dimethyl fumarate (2/21 exposed pregnancies), fingolimod (1/11 exposed pregnancies) and natalizumab (2/30 exposed pregnancies). After delivery, 18.8% of women with MS were escalated of DMT efficacy, while 50.7% started on same/similar-efficacy DMTs, and 30.5% did not receive DMT. The probability of breastfeeding was higher in women who were treated with breastfeeding-safe DMTs (OR 5.57; 95% CI 1.09 to 28.55; p=0.03). Conclusions: Fertility rate in women with MS remains below the general population. Family planning and subsequent DMT decisions should aim to achieve successful pregnancy, delivery and breastfeeding outcomes, while controlling disease activity.