IN THE 19TH CENTURY, the social ideal of the middle class American family changed dramatically. Families were smaller (about five kids) and more insular than the extended, utilitarian families of the colonial era. Marsh says a new philosophy arose about what the family meant. Where colonial women were central to economic production on the farm, 19th century women found their social sphere increasingly limited to the home.

"The family became more privatized, women became more responsible for what went on in the family," Marsh says. "Children became the purpose of family life -- especially middle and upper-middle class family life -- in a way that they hadn't been before."

Patent medicines for "female weakness" and infertility were sold widely in the 19th Century. [Library of Congress]

A woman who could not meet these expectations because of infertility became the object of pity, if not scorn. In 1861, a prominent Southern aristocrat named Mary Chesnut had been married for two decades but still had no children. At age 38, Chesnut was despondent. She agonized in her diary over the disdain she felt from her domineering in-laws.

"Women have such a contempt for a childless wife," Chesnut wrote in her diary. "Mrs. Chesnut (her mother-in-law) was bragging to me one day, with exquisite taste -- to me, a childless wretch -- of her twenty-seven grandchildren; and Colonel Chesnut, a man who rarely wounds me, said to her, 'You have not been a useless woman in this world.'" LISTEN

After the Civil War, birthrates plunged. Historians say the drop was largely voluntary; in tough economic times, couples had fewer children and more women passed their lives unmarried. By then, doctors knew that men could be infertile, but women still bore most of the blame. Infertile women were suspected of ignoring their proper domestic roles.

Nineteenth century physicians considered the female body a delicate vessel, easily damaged by unchecked social exertion or stress. In 1873, Harvard physician Edward H. Clarke wrote a widely acclaimed book, "Sex in Education, or A Fair Chance for Our Girls," which charged that education was the culprit for female sterility (as the condition was then called) by manufacturing women with "monstrous brains and puny bodies."

Clarke wrote: "The reproductive machinery, to be well made ... must be carefully managed. Force must be allowed to flow thither in an ample stream ... and not diverted to the brain by the school."

Part four: Race Suicide