Toxoplasmosis: maternal and pediatric findings in 23,000 pregnancies.

An analysis of the antibody titers to toxoplasmosis for 22,845 pregnant women in the Collaborative Perinatal Project was conducted in relation to clinical and laboratory findings in the mothers and children through 7 years of age. More than 900 observations were considered for each mother and child. The major findings were in the children and included a predicted doubling in the frequency of deafness among children born to women with antibody to toxoplasmosis, a predicted 60% increase in microcephaly, and a 30% increase in low IQ (less than 70) in association with the presence of high maternal antibody titer (256 to 512) to toxoplasma. A serologically defined high-risk group of mothers was identified on the basis of high indirect hemagglutination antibody levels or seroconversions and increased IgM toxoplasma antibody levels (indirect fluorescent antibody greater than or equal to 32, enzyme-linked immunosorbent assay greater than or equal to 0.7). Of the 15 pregnancies in this group, two children had congenital toxoplasmosis and three were stillborn.