Low titers of measles antibodies in Japanese pregnant women: A single-center study

Aim: Measles during pregnancy has deleterious effects on both perinatal and maternal outcomes. In Japan, local epidemics of measles and cases of measles during pregnancy are still being reported; therefore, the seroprevalence of antibodies to measles is suspected to be still not sufficient. The aim of this study was to analyze the seroprevalence of antibodies to measles in Japanese pregnant women and estimate the percentage of these women who require vaccination or revaccination against measles. Material and Methods: We analyzed the seroprevalence of immunity to measles by the neutralization test in 10 349 pregnant women in the first trimester managed at the National Center for Child Health and Development between February 2004 and December 2010. The neutralization test titers were interpreted as follows: ?1:8, seropositive; = 4, low-positive; ?4, seronegative. Results: Of the total number of pregnant women tested, 7408 (71.6%) were seropositive, 1864 (18.0%) were low-positive, and 1079 (10.4%) were seronegative for measles antibodies, respectively. Conclusion: Our results revealed that 28% of our pregnant population was seronegative or low-positive for measles antibodies, and thought to require revaccination or vaccination. Screening for measles immunity might be advisable for women of childbearing age.