Importance: Risk of relapse may be increased in the postpartum period of neuromyelitis optica spectrum disorder (NMOSD). Information regarding factors associated with pregnancy-related attacks is still lacking.
Objectives: To identify factors associated with pregnancy-related NMOSD attacks, investigate the integrated annualized relapse rate (ARR) and Expanded Disability Status Scale (EDSS) score in each phase of pregnancy, and summarize pregnancy outcomes and complications in patients with NMOSD.
Data sources: An electronic search was performed in the MEDLINE, PubMed in-process and non-MEDLINE, EMBASE, Web of Science, and Cochrane databases using the OvidSP search platform, updated through December 30, 2021.
Study selection: All published and unpublished studies in English were considered, covering all patients with NMOSD with an informative pregnancy.
Data extraction and synthesis: Two independent reviewers extracted the published data with a standardized procedure following MOOSE and PRISMA guidelines. The end points were calculated with the DerSimonian and Laird inverse variance (for random effects) method.
Main outcomes and measures: The primary outcome was the rate of pregnancies with pregnancy-related NMOSD attacks, measured by risk ratios (RRs). The mean differences (MDs) in ARR and EDSS scores between each phase of pregnancy, pregnancy outcomes, and complications were defined as the secondary outcomes.
Results: A total of 15 studies were analyzed, including 443 patients with NMOSD with 639 informative pregnancies. Patients receiving immunosuppressive treatment during pregnancy (RR, 0.43; 95% CI, 0.32-0.57; P < .001) and with older age at conception (RR, 0.67; 95% CI, 0.47-0.95; P = .02) had lower rates of pregnancy with pregnancy-related attacks. The increase in the ARR was highest in the first trimester after delivery compared with before pregnancy (MD, 1.28; 95% CI, 0.94-1.62; P < .001). The EDSS scores increased significantly both during pregnancy (MD, 0.44; 95% CI, 0.20-0.69; P < .001) and in the postpartum period (MD, 0.88; 95% CI, 0.51-1.26; P < .001) compared with before pregnancy.
Conclusions and relevance: This systematic review and meta-analysis found that receiving immunosuppressive treatment during pregnancy and older age at conception were associated with reduced risk of pregnancy-related NMOSD attacks, which mostly occurred in the first trimester of the postpartum period, although more high-quality prospective studies are needed.