IStock Photo 1141281 © Tina Sbrigato

In 1995, women of the United Kingdom went on a massive birth control strike. The British Committee on Safety of Medicines announced that third-generation progestogen pills carried twice the risk of blood clots as did second-generation pills, and 41% of women stopped taking their oral contraceptives immediately. Sixty-one percent stopped within a month. In the following year the abortion rate rose considerably.

“Twice the risk” sounds bad. But what’s actually dangerous—far more dangerous than blood clots—is making decisions without putting risks in perspective. “If you’ve got a very low risk to begin with, and then you double it, it’s still a very low risk,” says Felicity Goodyear-Smith, who studies risk communication at the University of Auckland Faculty of Medical and Health Sciences.

In fact, the absolute risk of blood clot between second- and third-generation pills went up by only 1 in 10,000. And if blood clots are your concern, consider this: you’re 20 times more likely to get a blood clot due to pregnancy than due to third-generation birth control pills.

The odds a sexually active female in the US aged 15 - 44 has ever taken the pill for contraceptive reasons are 1 in 1.22 (82%) (Even more, 1 in 1.11 (90%), has used condoms). And many of the 1 in 3.42 women who stopped using it did so out of concern about side effects: those odds are 1 in 7.63 (about the same as the odds, 1 in 7.58, that a woman stopped using condoms because she worried they would not work).

Oral contraceptives affect women’s bodies in so many ways that the side effects are both positive and negative. At least one study showed that the many odds of birth control cancel each other out. For example, second-generation pills may have a lower risk of clotting (which has a 1-2% fatality rate), but they also carry a higher risk of heart attack (up to a 50% fatality rate). Oral contraception is good for ovarian cancer, bad for circulatory diseases, and in the end it all adds up to zero: women who have taken the pill are just as likely to die in a given year as women who never have.