Severe infections of many kinds can lead to fetal death, abortion, or premature birth. Less severe infections lead to morphological malformations if they occur early enough in pregnancy or to functional disorders if they occur later; and mild infections lead to subtle disturbances or perhaps none at all. Hypothetically, there are at least five points at which the human fetus could be affected. These will now be considered.
Unfertilized Egg or Germinal Epithelium
The possibility that viruses may infect unfertilized eggs is intriguing, raising the idea of vertical transmission from generation to generation. Mumps virus certainly infects the ovaries and coxsackievirus B and other agents are probably also capable of doing so. However, these agents are usually lytic and would be expected to destroy the eggs.Lymphocytic choriomeningitis virus has been identified in the germinal epithelium of mouse ovaries, and this is presumably the means by which carrier mice pass