A prospective study of acquired toxoplasmosis among 8,043 pregnant women in the Oslo area.

A prospective serologic study of acquired toxoplasmosis has been carried out among 8,043 pregnant women in the Oslo area by means of the DT and IgG-IFAT tests on paired blood samples collected on an average in gestational weeks 13 and 35. The screening results indicated that 54 women had to be considered as having potential "risk pregnancies" and they were selected for special follow-up studies. Thirteen women were found to have acquired a toxoplasma infection during pregnancy. The outcome of these pregnancies was: two spontaneous abortions and probably four congenitally infected children. In three of these cases parasites could be demonstrated in the placenta and/or amniotic fluid. This gives a transmission rate of 46% and an incidence of congenital toxoplasmosis of nearly 1/1,000 births.