Twenty-two years screening for toxoplasmosis in pregnancy: Liege-Belgium.

Between 1966 and 1987, in Liége--Belgium, 20,901 pregnant women were screened for toxoplasmosis. In this period an increase in seronegative women from 30% to 53% and a decrease in the seroconversion rate from 6.4% to 1.2% was observed. This decrease could be the result of advice and prophylactic measures. Due to the low rate of seroconversion (actually less than 1%), the cost/effectiveness of a systematic screening and fetal diagnosis should be investigated.