Perinatal infections and immunity.

An increasing number of infectious agents are now recognized to be important causes of perinatal morbidity and mortality. Most of these agents produce asymptomatic or mild infections in the mother; however, some can cause severe or fatal disease in the fetus. In each case, the infectious agent is transmitted from the mother to the child, usually by the transplacental, hematogenous route. The time of maternal infection during gestation frequently influences the chance of fetal infection and severity of fetal disease. The pathogenesis of these infections involves direct infection of the developing fetal tissues. In some cases this infection can interfere with morphogenesis or cause severe tissue destruction. Very late effects are now recognized with some perinatal infection, thus it is important to conduct longitudinal studies of infected children. Fetal disease can be prevented or reduced if prior exposure of the mother has resulted in complete or partial immunity. Immune responses in the fetus, which become detectable at about 20 to 22 weeks gestation, can be used for diagnostic purposes. They also appear to provide some degree of protection of the fetus from severe or fatal disease with certain agents when infection occurs late in gestation. The prevention of fetal damage by perinatal infections can be accomplished by protection of the mother through the appropriate use of vaccines, avoidance of exposure, treatment with immunoglobulins or the use of chemotherapy. Treatment of the child also involves the use of immunoglobulins and chemotherapy.