But it stirred up a lot of debate. “I was shocked, frankly,” she said, especially by the fears that the product unleashed in the United States. When a mail-order New York firm tried to sell Organon test kits to American consumers in 1971, it faced opposition from the United States Public Health Service. In 1973, a New Jersey drugstore bought kits made by the drug company Roche and offered fast and private tests to their customers, and though the technology was similar to that available in medical clinics, the state medical examiner questioned the legality of the service.

Why so much opposition? Some regulators worried that “frightened 13-year-olds” would be the main users of the test kits. But after the product did become available in the United States in 1977, it appealed instead to college-age and married women — many of whom desperately hoped for children.

Even so, the Texas Medical Association warned that women who used a home test might neglect prenatal care. An article in this newspaper in 1978 quoted a doctor who said customers “have a hard time following even relatively simple instructions,” and questioned their ability to accurately administer home tests. The next year, an article in The Indiana Evening Gazette in Pennsylvania made almost the same claim: Women use the products “in a state of emotional anxiety” that prevents them from following “the simplest instructions.”

The tale of the home pregnancy test is not unique. Breakthroughs that give patients control over their bodies are often resisted. Again and again, the same questions come up: Are patients smart enough? Can they handle bad news? And do they have the right to private information about their bodies?

When home H.I.V. tests were being developed in the 1980s, they inspired the same kind of fears as the pregnancy test — including unfounded dread that if people learned bad news alone at home, many of them would kill themselves. The Food and Drug Administration approved the first home H.I.V. testing kit only in 1996. Customers would take a blood sample at home, mail it to a lab and hear results over the phone, often from a counselor. The first rapid, truly private H.I.V. home test didn’t reach drugstores until 2012.

Meanwhile, in most areas of the United States, women still need permission from a doctor to buy birth control pills, even though they are arguably safer than a lot of other drugs now sold over the counter and there are very few health risks involved. It’s true that some women with conditions like liver disease, breast cancer and hypertension may be at risk of developing complications from the pill, but labels can warn them against using it. We can trust women to figure this out.

Indeed, dozens of other countries make birth-control medications available to women without a prescription. According to a recent Reason-Rupe poll, 70 percent of Americans believe that we should follow their example.