Original article| Volume 44, 102241, September 2020

Change in pregnancy-associated multiple sclerosis relapse rates over time: a meta-analysis

  • Ruth Dobson
    Corresponding author: Dr. Ruth Dobson, Preventive Neurology Unit, Wolfson Institute of Preventive Medicine, Charterhouse Square, Queen Mary University London. Tel: 020 7882 6463. @drruthdobson.
    Preventive Neurology Unit, Wolfson Institute of Preventive Medicine, Queen Mary University London

    Department of Neurology, Royal London Hospital, BartsHealth NHS Trust
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  • Vilija G. Jokubaitis
    Department of Neuroscience, Central Clinical School, Monash University, Melbourne
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  • Gavin Giovannoni
    Preventive Neurology Unit, Wolfson Institute of Preventive Medicine, Queen Mary University London

    Department of Neurology, Royal London Hospital, BartsHealth NHS Trust

    Blizard Institute, QMUL
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      • The historic assumption that MS relapse rate reduces during pregnancy and increases again post-partum remains true, despite significant changes in the MS treatment landscape, and increasing rates of treatment with DMT.
      • MS relapse rate appears to be decreasing over time in women both prior to pregnancy and in the post-partum period.
      • Neither diagnostic criteria, DMT exposure, nor proportion of women breastfeeding appears to associate with the change in relapse rate at a population level.



      Women with MS are advised that relapse rates fall during pregnancy and rebound post-partum. This advice originates from 1998; smaller, more recent, studies have not been previously pooled.


      All studies published since 1998 providing raw relapse data were considered for inclusion. Single arm meta-analysis was performed using a restricted maximum likelihood random effects model with inverse variance; secondary subgroup analysis and meta regression were then performed. Annualised relapse rates (ARR), or relapse numbers/rates suitable for conversion into ARR during pregnancy and the post-partum period were included. Secondary subgroup analysis examined year of data collection, DMT exposure, breastfeeding and data source.


      7034 pregnancies from 6430 women were included. ARR fell from 0.57 (95%CI 0.45-0.70) pre-pregnancy to 0.36 (0.28-0.44), 0.29 (0.21-0.36) and 0.16 (0.11-0.21) during trimesters 1,2, and 3, with a post-partum rebound (ARR 0.85, 95%CI 0.70-1.00). ARR reduced pre-pregnancy and post-partum over time (p<0.001). Relapse rates were lower in claims databases than elsewhere.


      Despite high heterogeneity, we confirm the historic assumption that ARR reduces during pregnancy, and demonstrate an overall reduction in ARR over time. Studies using data originating from claims databases demonstrated a lower relapse rate at all time points, which has not previously been demonstrated.


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