What it used to be called:
Medicalized childbirth became an option.
During the second half of the twentieth century, with the growing popularity of Caesarean sections, labor inducing drugs, and epidural anesthesia, natural childbirth was conceived to describe labor and delivery without surgery and with minimal or no use of drugs or anesthetics.
An early use:
In a letter to Time magazine in Feb 9, 1953, Francella R. Poston wrote: "Natural childbirth is no craze. It is the desire of a group of healthy, well-adjusted women to go about having their babies naturally...."