Which infection is known for being transmitted from the mother to the fetus through the placenta?

Toxoplasmosis is notably transmitted from the mother to the fetus through the placenta, making it a significant concern during pregnancy. The parasite responsible for toxoplasmosis, Toxoplasma gondii, can cross the placental barrier, leading to potential complications for the developing fetus. These complications may include congenital defects, developmental delays, or even stillbirth, depending on the timing of the infection during the pregnancy.

In contrast, while chlamydia can be transmitted from mother to child during delivery and can potentially lead to eye infections and pneumonia in the newborn, it is not typically transmitted through the placenta. Herpes simplex virus can also be a concern during delivery if the mother has an active outbreak, but, like chlamydia, it is primarily transmitted during the birthing process rather than transplacentally. Group B streptococcus poses risks during labor and delivery as well; it can cause infections in the newborn if not managed properly but does not involve transmission through the placenta. Thus, toxoplasmosis stands out as the primary infection related to transplacental transmission.