The helpless newborn has not always evoked a protective and loving response, in part because the newborn was not always believed to be human.This belief legitimized an action that under other circumstances would be referred to as murder.Changelings were infants believed to be exchanged in the still of the night by devils or goblins who removed the real child and left the changeling in its place.
The Roman emperor Constantine, a Christian convert, proclaimed the slaying of a child by the child's father to be a crime.
Infanticide was punishable by the death penalty by the end of the fourth century.
Despite human repugnance for the act, most societies, both ancient and contemporary, have practiced infanticide.
Based upon both historical and contemporary data, as many as 10 to 15 percent of all babies were killed by their parents.
Neonaticide is generally defined as "the homicide of an infant aged one week or less." The psychiatrist Phillip Resnick further limits neonaticide to the killing of an infant on the day of its birth.