The placental transmission of immune antibodies to the newborn had been inferred by clinical observation for some years before Ehrlich proved its occurrence experimentally in 1892.1 Since that time the transplacental passage of humoral antibodies has claimed the interest of many investigators who have made highly significant contributions to the basic knowledge of placental physiology and immunology. Practical results of their work have come from a clearer understanding of the previously observed neonatal immunity of many infants to infections which attacked them later in life. The relatively short duration of the newborn's passively acquired immunity has been well established by many of these investigations,2-17 and a pattern of artificial immunization for infants has been devised as a result. The practice of actively immunizing expectant mothers in order to protect newborn infants was advocated even in the pre-Ehrlich era 18 and has been proposed anew in more recent times.
ZEIDBERG LD, GASS RS, HUTCHESON RH. The Placental Transmission of Histoplasmosis Complement-Fixing Antibodies. AMA Am J Dis Child. 1957;94(2):179–184. doi:10.1001/archpedi.1957.04030030073011