Low IgG avidity and ultrasound fetal abnormality predict congenital cytomegalovirus infection

Cytomegalovirus (CMV) causes congenital infection with high mortality and morbidity rates in affected neonates. The aim of this study was to assess whether prenatal clinical or laboratory findings in pregnant women who had high risks for primary CMV infection predicted the presence of congenital infection. Fifty pregnant women who had serum CMV IgG and positive or borderline tests for serum CMV IgM were included in this prospective study. Serum IgG avidity was measured, and PCR was conducted for CMV DNA in maternal serum, urine, and uterine cervical secretion. All neonates underwent PCR testing for CMV DNA in the urine for the presence of congenital infection. Risk factors were compared between congenital infection group and group without congenital infection. As a result, nine neonates (18%) were diagnosed as having congenital infection. The frequencies of ultrasound fetal abnormality and positive test for CMV DNA in cervical secretion, CMV IgM titer and IgM/IgG ratio in the congenital infection group were significantly higher than those in the group without congenital infection. Conversely, IgG avidity index in the congenital infection group was significantly lower than that in the group without congenital infection. By multivariate logistic regression analyses, IgG avidity index (Odds ratio 0.91, 95% CI: 0.83-0.99) and ultrasound fetal abnormality (291.22, 2.72-31125.05), were selected independently as significant signs predictive of congenital CMV infection. Among pregnant women with positive or borderline tests for CMV IgM, when they have findings of low serum CMV IgG avidity or ultrasound fetal abnormality, the probability of congenital CMV infection may increase.