【Objective】To compare the differences of neuromyelitis optica spectrum disorder（NMOSD）and multiple sclerosis （MS） on pregnancy，and analyze the mutual impact of pregnancy on the diseases.【Methods】Prospectively collected clinical information of 235 NMOSD patients and 125 MS patients，including the annualized relapse rate（ARR），the Expanded Disability Status Scale（EDSS）and pregnancy outcomes. 70 NMOSD patients and 30 MS patients were screened out as information patients. The ARR and EDSS score in two groups were compared during the year before pregnancy，during pregnancy and after 1 year postpartum， respectively. 50 cases of normal pregnant women for the same period as the control group，then to compared the difference of three groups on pregnancy outcomes.【Results】Attacks occurring during pregnancy or one year after childbirth/abortion in NMOSD and MS were 53.25%（41/77）and 20.00%（7/35）（P = 0.001）；The ARR during the first 3 months postpartum periods of NMOSD and MS group（2.65，2.51）was significantly higher than during the year before pregnancy（0.27，0.49，P < 0.001）and during pregnancy （0.32，0.2，P < 0.001）；The EDSS score of two groups increased after 1 year postpartum（3.06 ± 2.16，2.19 ± 1.28）than that during the year before pregnancy（1.58 ± 0.48，1.92 ± 1.29，P < 0.001）and during pregnancy（1.92 ± 1.35，1.67 ± 0.70，P < 0.001）.There was no difference on ARR and EDSS score between NMOSD and MS group. NMOSD，MS and normal control group had no dif? ference on pregnancy outcomes and neonatal weight.【Conclusions】Compared with MS，the attack of NMOSD had more closer relation? ship with pregnancy；both NMOSD and MS would increase the risk of disease relapsing and disability after pregnancy；the diseases had no effect on pregnancy outcomes.