Historical Look at Childbirth in the US, 1750-1975
This figure show all sorts of things in the history of US childbirth - % midwife attended births over time, % hospital births over time, % of births using anesthesia ... Figure from:
Leavitt, Judith Walzer. 1986. Brought to Bed: Childbearing in America 1750 to 1950. New York: Oxford University Press.