What is the process by which antibodies are transferred from mother to fetus during pregnancy called?

The transfer of antibodies from mother to fetus during pregnancy is known as passive immunity. This process occurs naturally when the mother's immune system produces antibodies that are then passed through the placenta to the developing fetus. This transfer provides the newborn with immediate protection against certain infections during the first few months of life, as the infant's own immune system is not fully developed at birth.

Passive immunity is characterized by the immediate availability of antibodies without requiring the infant's immune system to actively produce them. This is distinctly different from active immunity, where an individual's own immune system generates a response to a pathogen or vaccine. In terms of artificial immunity, that involves immunity gained through medical interventions, such as vaccinations or serum injections, which is not the case during the natural maternal-fetal antibody transfer. Immunization refers specifically to the process of stimulating an immune response through vaccination, which does not apply to the direct transfer of maternal antibodies.