The world's most popular birth control method may surprise you

When you think of contraception, it's likely that condoms and the birth control pill first come to mind. Those are, after all, the most common methods, right? They are what get high-profile television advertisements and spark contentious public debate here in the United States. But it turns out they are among the least common methods used around the world. In fact, they rank only slightly more common than the rhythm method or withdrawal.

In honor of World Contraception Day, which falls on September 26, we took a look at data around birth control-use worldwide — and some of the most common birth control is pretty surprising. Perhaps most of all that the leading method of contraception is female sterilization, a surgery where a woman is permanently rendered infertile.

Last year, 19 percent of women around the globe who were married or in a relationship relied on sterilization, according to a report by the United Nations. Next most common was the IUD, a little pregnancy-preventing device that's inserted into the uterus, which was used by 14 percent of partnered women around the world. Much less common were short-term methods, including the birth control pill (9 percent), the male condom (8 percent), and injectibles like Depo-Provera (5 percent). Compare those numbers to the 6 percent of women who used the rhythm method or withdrawal.

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Surprising as it may be, there's every reason to celebrate this as good news — long-acting methods like the IUD tend to be more effective because they leave little room for inconsistent use (i.e. missed pills or running out of condoms).

There's also this positive finding: The overall prevalence of contraception has nearly doubled since 1970, from 36 percent to 64 percent in 2015. That is to say: The majority of partnered women around the world now use some form of contraceptive. These numbers are much less encouraging among the least developed countries, where that number drops to just 40 percent. In Africa, it is just 33 percent. At the opposite end of the spectrum is China, which only this year ended its infamous one-child policy, with 84 percent of women using contraception. Close behind is Northern Europe, with 77 percent, and North and South America, with 75 percent each.

In the coming decades, those numbers are expected to shoot up. By 2030, the UN predicts that the number of partnered women using contraception will rise by 20 million to nearly 800 million. But, it's World Contraceptive Day, which has the stated aim of a world "where every pregnancy is wanted," so we'd be remiss to end on that sunny note. While the situation has certainly dramatically improved, the number of women worldwide who want contraception but don't have access is actually expected to change relatively very little: from 142 million to 143 million by 2030. That's thanks to growing contraceptive demand and rising numbers of reproductive-age women in sub-Saharan Africa.

So, unfortunately, it looks like the need for World Contraceptive Day isn't going away any time soon.

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