Pregnancy-related relapse risk factors in women with anti-AQP4 antibody positivity and neuromyelitis optica spectrum disorder

Background: Few reports describe the influence pregnancy has on the annualized relapse rate (ARR) in neuromyelitis optica spectrum disorder (NMOSD). Objective: To examine pregnancy-related attacks (attacks during pregnancy or within 1 year postpartum) and identify the risk factors for an attack in Japanese NMOSD patients. Methods: We retrospectively reviewed 139 Japanese women whom had aquaporin-4 (AQP4) antibody-positive NMOSD. Among the 114 patients with information, 47 women had 56 pregnancies. We compared the ARR before, during and after pregnancy. Results: Of the 47 NMOSD patients with pregnancy, 22 women (46.8%) had a pregnancy-related attack of the disease (either an onset event or a relapse). The ARR was significantly higher in the first 3 months postpartum (1.80 ± 2.04), than before the pregnancy (0.57 ± 1.16; p = 0.0043) and did not significantly decrease during pregnancy. The ARR before hospitalization and treatment was analyzable in 55 patients without pregnancy and was 1.09 ± 1.17. Among the 11 patients with onset before pregnancy, nine patients had a pregnancy-related attack with a relapse in the previous year, and their immunosuppression was discontinued or made to be at low doses; while the two patients on higher-dose therapies were relapse-free. Conclusion: In the present study, pregnancy-related attack was common in NMOSD, and unlike in multiple sclerosis, the ARR was not reduced during pregnancy. Discontinued or insufficient immunosuppression appeared to increase the risk of pregnancy-related attack.