What’s the Most Effective Method of Contraception, by Far?

Health and medicine explained.
July 31 2012 11:30 AM

Why Have Teen Pregnancy Rates Dropped?

A new study shows how to reduce them even more.

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And therein lies the catch. In the real world, only 40 percent of adults and 25 percent of teens actually remember to take the pill every day, which makes the real-world risk of pregnancy much higher than expected.

Earlier this year, Washington University researchers led by Jeff Peipert reported in the New England Journal of Medicine that 5 percent of women in a study who were on the pill got pregnant within a year. Among those under 21 years of age, almost twice as many did. Take a moment to reflect on that. Imagine you are a concerned parent who accepts that your high school senior has sex. You take her to the doctor and she starts taking the pill. The data show that this is much better than just telling her to use a condom during intercourse. However, before graduation, 1 in 10 such girls will be headed for the delivery room or abortion clinic. That is a breathtaking failure rate.

Peipert’s study included almost 10,000 women given their choice of free contraception. It was funded not by federal grants (which almost never pay for contraception research), but by a private foundation endowed by the iconoclastic wife of investor Warren Buffett. The study points a clear way forward for reducing unwanted pregnancies. To begin with, when contraception was free, almost three-quarters of teens and adult women chose intrauterine devices like Mirena or ParaGard, which last five to 10 years, over alternatives like the pill, contraceptive patch, cervical ring, or Depo-Provera. (Modern IUDs can be implanted easily in young teens and do not carry additional risks of pelvic infection.) Similarly, IUD adoption doubled in California when the devices were made free.

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But the most dramatic result of Peipert’s study was that the risk of contraceptive failure was 22 times higher with the pill than with IUDs in adult women, and double that for teens. Just imagine, Peipert recently told me, if a miracle drug suddenly slashed cancer deaths or heart attacks by 95 percent. Every patient would demand it and no one would want the older therapies. The parent in the above example would sleep better at night knowing the teen’s risk of pregnancy was only 0.3 percent, instead of 10 percent. However, only 2 percent of teens and 4 percent of American women now get IUDs. More couples than that rely on withdrawal, which has an estimated 25 percent risk of failure, as their preferred contraceptive method.

Peipert makes another persuasive argument. Though this aspect of his research is still in peer review and awaiting publication, he suspects that the abortion rate can drop by half when women are given free access to IUDs. Again, imagine if a magic treatment suddenly made half the country’s abortions unnecessary. For what good reason would anybody be opposed?

Vermont provides a good example of how contraception research can improve public health. The state has the country’s lowest teen pregnancy rate and highest use of teen contraception. Breena Holmes, a pediatrician who directs the state’s department of maternal and child health care, points out that the American Congress of Obstetricians and Gynecologists still doesn’t promote the massive advantages of IUDs over the pill. Though Medicaid covers IUDs, there’s usually only a one-time payment, which may be insufficient for follow-up care. (For example, many women may have spotting and might require a subsequent pelvic exam or other testing, although the problem generally improves a few months after implantation.) To get around these obstacles, Holmes explains, Vermont engineered innovative federal payment schemes in association with Planned Parenthood to expand reproductive health services and dismantle barriers to IUD availability.

For decades, battles over reproductive health in teens have focused on sex ed in schools. But the decline in teen pregnancy since 1990 shows that the big changes occur only when we also treat reproductive health just like every other kind of medical science—by discarding problematic treatments and aggressively promoting effective ones.

Darshak Sanghavi, a pediatric cardiologist, is a fellow of the Brookings Institution and Slate’s health care columnist. Follow him on Twitter.