Immunological characteristics of pregnant women, fetuses and newborns and measures for preventing mother-to-infant vertical infection

This study of mother-infant immune system using in vitro and in vivo models and clinical settings was undertaken to examine immunological determinants of mother-to-infant vertical infection and to determine appropriate treatment methods. 1. Since pregnant women have a suppressed immune status, reflected in decreased Th1 cell counts and associated decreased function of both cytotoxic T cells and NK cells, they are susceptible to viral infection. For this reason, viral infection is severe in pregnant women, and is usually treated by administration of neutralizing antibody. 2. The immune system remains immature even in full-term newborns. Fetuses under hypoxic conditions, intrauterine growth retardation (IUGR) infants, preterm infants (less than 32-week-gestation), and newborns immediately after birth are particularly immunodeficient. It is thus recommended that measures, such as washing of hands, for preventing infection be taken into account in neonatal management. 3. Pregnant women have a transplacental IgG transfer mechanism to compensate for the immature immune system of the fetus, however, the mechanism does not function sufficiently in preterm infants or IUGR infants. It is thus necessary to administer IgG after birth. IgA and TGFβ in breast milk act as a second support mechanism of the immune system of infants after birth. For this reason, it is recommended that breast feeding be actively given particularly to preterm infants and IUGR infants. 4. While lymphocytes in breast milk transmit immunological information to infants, HTLV-I can cause vertical infection through breast milk. In this case, breast feeding should be terminated. Conclusion: There is an immunological supporting system in pregnant women which compensates for the immunodeficient status of infants. Devising treatment methods and preventive measures on the basis of the knowledge of characteristics of the mother-infant immune system will lead to better therapeutic outcome.