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ObjectivePregnancy has a well documented effect on relapse risk in multiple sclerosis (MS). Prospective studies have reported a significant decline by two-thirds in the rate of relapses during the third trimester of pregnancy and a significant increase by two-thirds during the first 3 months postpartum. However, it is unclear as to whether there are any long term effects on disability.MethodsData were collated from clinical records and family histories systematically collected from the University of British Columbia MS Clinic.ResultsClinical and term pregnancy data were available from 2105 female MS patients. MS patients having children after MS onset took the longest time to reach an Expanded Disability Status Scale (EDSS) score of 6 (mean 22.9 years) and patients having children before MS onset were the quickest (mean 13.2 years). However, these effects were not related to term pregnancy and were fully accounted for by age of MS onset.ConclusionsPregnancy had no effect on the time to reach an EDSS score 6. As MS predominantly affects women of childbearing age, women with MS can be reassured that term pregnancies do not appear to have any long term effects on disability. [ABSTRACT FROM AUTHOR]

Summary: Background: HLA-DRB1*15 genotype, previous infection with Epstein-Barr virus, and vitamin D insufficiency are susceptibility factors for multiple sclerosis, but whether they act synergistically to increase risk is unknown. We aimed to assess the contributions of these risk factors and the effect of established precursors of multiple sclerosis, such as brain lesions on MRI and oligoclonal bands in CSF at the time of incident demyelination, on development of multiple sclerosis in children. Methods: In our prospective national cohort study, we assessed children who presented with incident CNS demyelination to any of the 16 paediatric health-care facilities or seven regional health-care facilities in Canada. We did univariate and multivariable analyses to assess contributions of HLA-DRB1*15, Epstein-Barr virus, vitamin D status, MRI evidence of brain lesions, and CSF oligoclonal bands as determinants of multiple sclerosis. We used classification and regression tree analyses to generate a risk stratification algorithm for clinical use. Findings: Between Sept 1, 2004, and June 30, 2010, we screened 332 children of whom 302 (91%) were eligible and followed-up for a median of 3·14 years (IQR 1·61–4·51). 63 (21%) children were diagnosed with multiple sclerosis after a median of 127 days (99–222). Although the risk of multiple sclerosis was increased with presence of one or more HLA-DRB1*15 alleles (hazard ratio [HR] 2·32, 95% CI 1·25–4·30), reduced serum 25-hydroxyvitamin D concentration (HR per 10 nmol/L decrease 1·11, 1·00–1·25), and previous Epstein-Barr-virus infection (HR 2·04, 0·99–4·20), no interactions between these variables were detected on multivariate analysis. Multiple sclerosis was strongly associated with baseline MRI evidence of one or more brain lesion (HR 37·9, 5·26–273·85) or CSF oligoclonal bands (6·33, 3·35–11·96), suggesting established disease. One patient diagnosed with multiple sclerosis had a normal MRI scan, and therefore sensitivity of an abnormal MRI scan for multiple sclerosis diagnosis was 98·4%. Interpretation: Risk of multiple sclerosis in children can be stratified by presence of HLA-DRB1*15 alleles, remote Epstein-Barr virus infection, and low serum 25-hydroxyvitamin D concentrations. Similar to previous studies in adults, brain lesions detected on MRI and CSF oligoclonal bands in children are probable precursors to the clinical onset of multiple sclerosis. Children with a normal MRI are very likely to have a monophasic illness. Funding: Canadian Multiple Sclerosis Scientific Research Foundation. [Copyright &y& Elsevier]