Neonatal outcome in women with multiple sclerosis – influence of disease activity: A Danish nationwide cohort study

Background Maternal multiple sclerosis (MS) has been associated with an increased risk of adverse birth outcomes. We hypothesized that active disease during conception and pregnancy plays an important role in this context, which this study aims to address. Methods We used the Danish registers to conduct a nationwide cohort study. Information on maternal disease activity during pregnancy was retrieved using proxies from the linked registers (hospitalization, magnetic resonance imaging of the brain, and use of systemic corticosteroids during pregnancy). Neonates, exposed in utero to maternal disease activity constituted the exposed cohort and the unexposed cohort constituted neonates without in utero exposure to maternal disease activity. The examined outcomes were preterm birth, small for gestational age, low 5-minute Apgar score, and major congenital anomalies. In logistic regression models we estimated the odds ratios (OR) with adjustment for confounders such as maternal age, comorbidities, parity, smoking, calendar year of birth, and disease-modifying treatment. Results Among the study population of 2,492 children of mothers with MS we identified 273 (11%) neonates exposed to maternal disease activity during pregnancy, and 2,219 (89%) neonates without exposure to disease activity. The adjusted odds ratios (aOR) for preterm birth, small for gestational age, low 5-minute Apgar score, and major congenital anomalies among children born by women with disease activity during pregnancy were 0.92 (95% confidence interval (95% CI) 0.53-1.60), aOR 1.19 (95% CI 0.62-2.26), aOR 2.57 (95% CI 0.93-7.15) and aOR 0.93 (95% CI 0.48-1.83), respectively. Conclusions Women with MS having disease activity during pregnancy did not have a statistically significantly increased risk of adverse neonatal outcomes compared to women with MS without disease activity, which is overall reassuring results. We believe, that this will be useful knowledge for patients and clinicians in planning a pregnancy and preparing a birth plan.