worth of an infant is not an acceptance of infanticide.
Today in most cases infanticide is treated more leniently than death of an adult. not very different from then.
Of course the worth of human life was elevated in late Roman times on in western civ through the spread of Christianity.
Those are human beings. They have rights the moment they are born. In fact, right here in California there was a preborn human who had rights before her mother was murdered, the Scott Peterson case where he went up for murder of 2 instead of just 1.