Next month marks the 50th anniversary of the birth-control pill in the U.S. The dawn of dependable contraception not only ended the post-war baby boom, it also ignited the sexual revolution and helped millions of women to enter the work force.

Nowadays, women can choose from a bevy of birth-control options, including pills, patches and rings that allow them to have as few periods as they like, even none. Implants and intrauterine devices (IUDs) can prevent pregnancy for years at a time and eliminate the need to refill and...