Cytomegalovirus seroprevalence among pregnant women in Nagasaki, Japan.

BACKGROUND: Cytomegalovirus (CMV) infection in pregnant women can result in congenital disease. Since the transplacental transmission rate is considerably higher in primary maternal infections than in non-primary infections, understanding CMV seroprevalence among pregnant women is crucial for increasing the implementation of preventive healthcare. METHODS: A population-based cross-sectional cohort study was conducted between 2014 and 2017 in Nagasaki City (the capital) and in Goto City, a remote island in Nagasaki Prefecture. We collected blood samples from pregnant women around 12 gestational weeks, and measured CMV-specific IgG antibodies using an enzyme immunoassay. We also investigated maternal age, gestational age, and the number of previous births at the time of blood sampling. RESULTS: We analyzed 8,901 subjects (8,388 cases in Nagasaki City and 513 cases in Goto City). The CMV seropositive rate was 78.2% in Nagasaki City, which had declined by 9% over 13 years, and 81.3% in Goto City, with no significant difference between the two regions (p = 0.0951). A multivariate logistic regression analysis revealed significant correlations between the CMV seropositive rate and maternal age (odds ratio 1.012 [p = 0.0172, 95% CI: 1.002-1.023]) or the number of previous births (odds ratio 1.363 [p <0.0001, 95% CI: 1.279-1.454]). CONCLUSIONS: A much higher risk of intrauterine CMV infection following maternal primary infection, a trend of decreasing CMV seropositivity, and an apparent risk of CMV infection during child-rearing indicate the necessity of preventive measures during the preconception period and during pregnancy.