Prenatal diagnosis of congenital toxoplasmosis.

Prenatal diagnosis of congenital toxoplasmosis was attempted in 50 pregnant women at risk for giving birth to an affected child. Fifteen of these patients seroconverted during pregnancy and 35 had a high initial antibody level in their first serum sample. Prenatal diagnosis consisted of a combination of ultrasound screening, amniocentesis, and funipuncture at about 20 weeks' gestation. Diagnosis of congenital toxoplasmosis was based on a positive toxoplasma culture of amniotic fluid or fetal blood and on the presence of specific immunoglobulin M antibodies in fetal blood. In addition, alterations in fetal hematology, cellular immunology, and fetal liver tests were indicative of infection. Fetal infection was detected in six fetuses; two died in utero as a consequence of the infection and four were born after 37 weeks' gestation. Despite antibiotic treatment with pyrimethamine and sulfadiazine, one child has internal hydrocephalus and chorioretinitis and another has unilateral chorioretinitis. In the two other children, the disease is still subclinical. Of the 44 children born after a negative prenatal diagnosis, 35 have reached the age of 1 year; toxoplasma antibodies have disappeared in all of them. Investigation of the remaining nine children showed a decrease in toxoplasma antibodies, suggesting that none of them are affected. Prenatal diagnosis was never associated with fetal loss, and premature delivery occurred in only two cases. We conclude that prenatal diagnosis of congenital toxoplasmosis is safe and reliable.