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8: Primary cytomegalovirus infection during pregnancy and subsequent congenital infection: maternal antibody screening involving 19,000 women

      Objective

      To identify the incidence rates of primary cytomegalovirus (CMV) infection during pregnancy and subsequent congenital CMV infection in Japan by conducting a maternal CMV antibody screening program in a large population of Mie Prefecture, Japan.

      Study Design

      We performed a population-based, observational, prospective cohort study. Women in early pregnancy were registered and tested for both CMV IgG and IgM antibodies. For the pregnant women who had positive results for both IgG and IgM antibodies, the IgG avidity index was measured. Those who had negative IgG antibody results were instructed by their obstetricians to take preventive measures against primary infection during pregnancy. Then, the women were retested for both IgG and IgM antibodies at late pregnancy. Primary infections were considered in the following two antibody screening results: one was positive IgG antibody, positive IgM antibody, and low IgG avidity index, and the other was IgG antibody seroconversion at late pregnancy from negative IgG antibody results at early pregnancy. For the pregnant women with primary infection, CMV DNA tests were performed for congenital infection.

      Results

      From September 2013 to March 2017, 19,435 pregnant women were registered in 24 centers in Mie Prefecture, Japan. Of 1,037 pregnant women with both positive IgG and IgM results, 115 showed a low IgG avidity index and were considered as having a primary infection. Of 6,636 pregnant women with negative IgG results at early pregnancy, only 4,082 were retested for IgG and IgM antibodies at late pregnancy, as 2,554 women had missing data. Of the 4,082 pregnant women with negative IgG results at early pregnancy, 31 showed IgG antibody seroconversion at late pregnancy and were considered as having a primary infection. Twenty-three women delivered a fetus with a congenital infection; 8 of 115 women had low IgG avidity index, and 15 of 31 women had IgG seroconversion. The observed incidence rates of primary and subsequent congenital infections were 0.75% and 0.12%, respectively (115 + 31 primary infection and 8 + 15 congenital infection, respectively). The estimated rates that the missing data were corrected were 0.85% and 0.16%, respectively (115 + 50 primary infection and 8 + 24 congenital infection, respectively).

      Conclusion

      The incidence rates of primary CMV infection during pregnancy and subsequent congenital CMV infection in Japan were estimated to be 0.85% and 0.16%, respectively.
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