The effects of pregnancy on relapse rates, disability and peripartum outcomes in women with multiple sclerosis: a systematic review and meta-analysis

Background: Although previous cohort studies of women with multiple sclerosis (MS) yielded a reduction in relapse rate during pregnancy, the effect size has not been quantified in a comprehensive manner. In addition, the effects on disability progression and peripartum outcomes have been controversial. The purpose of this work is to assess the effect of pregnancy on disease activity, and to assess the effects of MS on pregnancy as well. Materials & methods: We searched in PubMed, Cochrane Library and EMBASE for cohort studies dealing with the effects of pregnancy on relapse rates, disability progression and peripartum outcomes in women with MS. The evaluated outcomes were: changes in the annualized relapse rate (ARR) in pregnancy and puerperium, disability worsening compared with the year before pregnancy, and peripartum outcomes, which were compared with the ones of non-MS women. In the majority of cohorts included here, the women were not under disease modifying therapies during pregnancy. Results: We found 23 cohort studies measuring changes in the ARR during pregnancy and puerperium; 12 were prospective and 11 retrospective. In 17 cohorts there was significant reduction in the ARR during pregnancy compared with prepregnancy period. The pooled mean reduction in the ARR was -0.5 (95% CI: 0.67-0.38), p < 0.001, from 15 cohorts included in meta-analysis. In 18 cohorts the ARR increased in the 3-month puerperium relative to prepregnancy year period; the pooled mean increase in the ARR was 0.22 (95% CI: 0.11-0.33), p < 0.001, from 14 cohorts included in meta-analysis. Disability worsening was addressed in 18 cohorts, and in 14 of them there were no significant changes. Peripartum complications and obstetrical outcomes were assessed in 16 cohorts, of whom 13 were retrospective, without finding significant differences. Conclusion: Pregnancy is associated with lower disease activity, and puerperium with higher disease activity. Disability does not change significantly after pregnancy. The obstetrical outcomes are not very different from those of non-MS women in most cohorts.