Congenital infections affect the unborn fetus or newborn infant.
They are generally caused by viruses that may be picked up by the baby at any time during the pregnancy up through the time of delivery. The viruses initially infect the mother who subsequently may pass it to the baby either directly through the placenta or at the time of delivery as the baby passes through the birth canal. Mothers generally do not feel sick with the viruses. Sometimes they have flu-like symptoms. Even if the mother is known to have a viral illness during her pregnancy, her immune system may prevent the virus from infecting the fetus or newborn infant.