Abstract: Objective To study the level of specific antibody against Neisseria meningitidis serogroup A and C in pregnant women and their infants. Methods A longitudinal sero-epidemiology study was conducted in pregnant women and their infants to investigate the duration of the specific antibody against N. meningitidis serogroups A and C in pregnant women and infants at age of 0, 3 and 6 months. Results A total of 239 pregnant women and 241 infants were included in the study. The geometric mean concentrations (GMC) of specific antibody against N. meningitides serogroup A and C were 8.13 g/ml (95% CI:2.89-22.88) and 1.37 g/ml (95% CI:0.62-3.05), respectively in pregnant women before delivery. The GMC of specific antibody against serogroup A was 3.60 g/ml (95% CI:0.95-13.63) in the newborns and ranged from 2.85 g/ml to 3.59 g/ml in the infants aged 3-6 months, and the GMC of specific antibody against serogroup C increased from 0.49 g/ml (95% CI:0.15-1.63) at age 0 month to 5.49 g/ml (95% CI:2.04-14.75) at age 6 months in the infants. The specific antibody levels to N. meningitides serogroup A and C were lower in the infants than in the pregnant women. A significant positive correlation was observed in specific antibody levels to N. meningitides serogroup A and C between the pregnant women and the infants. Conclusion The specific antibody level to N. meningitides in the infants aged 0 month and 6 months was at critical level. It is necessary to strengthen the vaccination against meningococcal meningitis in infants and children.