Multiple Sclerosis and risk of eight Adverse Events in Pregnancy: a Mendelian Randomization study

Abstract Background Observational studies have found an association between multiple sclerosis (MS) and some adverse events in pregnancy, but the causal effect between them is unclear. Methods Using data from large-scale genome-wide association studies (GWAS), we performed two-sample Mendelian randomization (MR) analysis to comprehensively assess the causal relationship between MS and the risk of eight adverse events in pregnancy (gestational hypertension, diabetes mellitus in pregnancy, ectopic pregnancy, mental disorders, hemorrhage in pregnancy, intrahepatic cholestasis of pregnancy, infections of genitourinary tract in pregnancy, and postpartum hemorrhage). Results MR analysis found that MS significantly reduces the risk of diabetes mellitus in pregnancy [OR = 0.8718186, 95%CI (0.8298085, 0.9159556), P < 0.0001] and intrahepatic cholestasis of pregnancy [OR = 0.8813462, 95%CI (0.8052561, 0.9646262), P = 0.0061]. However, the causal effect of MS on the other six adverse events (gestational hypertension, ectopic pregnancy, mental disorders, hemorrhage in pregnancy, infections of genitourinary tract in pregnancy, and postpartum hemorrhage) was not statistically significant. Conclusion We found that MS significantly reduced the risk of diabetes mellitus in pregnancy and intrahepatic cholestasis of pregnancy, and the causal effect of MS on other six adverse events (gestational hypertension, ectopic pregnancy, mental disorders, hemorrhage in pregnancy, infections of genitourinary tract in pregnancy, and postpartum hemorrhage) is unclear.