The social science of IUDs

IUDs are the weird form of birth control. We don't really know exactly how they work, for instance. And they've been largely unpopular my entire lifetime—really, ever since a couple of poorly designed IUDs set off a mini-panic in the late 1970s and early 1980s. But IUDs are effective birth control. The ones that you can buy today are safe. And, more importantly, they represent birth control that you don't have to think about, and birth control that is really hard to get wrong.

If you've ever done research on the effectiveness of various methods of birth control, you'll notice that the statistics usually come with a little asterisk. That * represents a concept that few of the people who rely on birth control ever think about—perfect use. Let's use condoms as an example. With perfect use, 2 out of 100 women will get pregnant over the course of a year's worth of condom-protected sex. Without perfect use—maybe you don't use a condom every time, maybe you don't put it on right when you both get naked—the number of accidental pregnancies jumps to 18 out of 100. The same basic problem affects birth control pills, as well. Ladies, did you know you're supposed to take those things at the same time of day every day? That's the kind of use error that can make a difference between 1 out of 100 women getting pregnant in a year, and 9 out of 100 getting pregnant.

In contrast, IUDs represent a fit-it-and-forget-it method of birth control. Read the rest