This study investigated the prevalence of specific Toxoplasma gondii
IgG in pregnancy, the incidence of
congenital toxoplasmosis and the prevalence trend of T. gondii
infection among pregnant Polish women between 1998 and 2003. The study population comprised 4916 women who were admitted to the Polish Mother's Memorial Hospital Research Institute in Łódź. Their sera were tested for specific
IgG and
IgM antibodies to T. gondii, and the incidence of T. gondii
infection was calculated from the increase in prevalence rates of
IgG antibodies in various age groups. Specific
IgG antibody was found in 41.3% (95% CI 39.9-42.7) of pregnant women, and the prevalence of
IgG increased with age. The linear trend was significant (p <0.001), with an annual seroconversion rate of 0.7% (95% CI 0.004-0.010). The risk of primary
infection was estimated to be 0.5% for 9 months, i.e., an incidence of 5/1000 pregnancies. Assuming a 30% maternofetal transmission rate, 1.5/1000 neonates were infected in utero. Seroprevalence during the 6-year study period decreased from 45.4% in 1998 to 39.4% in 2003, with a yearly decline in prevalence of 1.0% (p 0.02). The most important contributory factor to this decline was the group of women aged 19-29 years, among whom seroprevalence decreased significantly (p 0.007). Specific
IgM was found in 244 (4.9%) women.