Congenital transmission
Toxoplasma gondii via maternal bloodstream infects the placenta
and then enters the fetal circulation. Maternal infection before
gestation poses little or no risk to the fetus except than women who
become infected just a few months (at the most three) before conception
(2). Transmission and severity of disease are determined by the
gestational age of which the mother became infected and they are
inversely related. So, maternal infection during the first and the
second trimester may result in severe congenital toxoplasmosis,
abortion, death of the fetus in uterus, perinatal death or stillbirth
despite the fact that during those trimesters the risk of congenital
transmission is reduced (less than 15% at 13 weeks of gestation) (3).
By contrast, maternal infection during the third trimester (late
infection) leads to a greater risk of subclinical infection in newborns
(up to 70%) (3-5).