In the 1950s, four people — the founder of the birth control movement, a controversial scientist, a Catholic obstetrician and a wealthy feminist — got together to create a revolutionary little pill the world had never seen before.

They were sneaky about what they were doing — skirting the law, lying to women about the tests they performed and fibbing to the public about their motivations.

"They absolutely could've been imprisoned for some of the work they were doing," journalist Jonathan Eig tells Fresh Air's Terry Gross. "These guys are like guerrilla warriors — they're always having to figure out ways to do this thing that will attract the least attention. ... They can never really say they're testing birth control."

Eig tells the history in his new book The Birth of the Pill: How Four Crusaders Reinvented Sex and Launched a Revolution.

The four people who created this revolution were: Margaret Sanger, who believed that women could not enjoy sex or freedom until they could control when and whether they got pregnant; scientist Gregory Pincus, who was fired from Harvard for experimenting with in-vitro fertilization and bragging about it to the mainstream press; John Rock, who was a Catholic OB-GYN and worked with Pincus to conduct tests of the pill on women; and Katharine McCormick, who funded much of the research.

In the '50s, selling contraception was still officially illegal in many states...