Birth Control Effect

Long-acting Reversible Birth Control Methods More Effective Than Pills, Patch, and Ring

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A study just published in the New England Journal of Medicine[1] to evaluate birth control methods has found dramatic differences in their effectiveness. Women who used birth control pills, the patch, or vaginal ring were 20 times more likely to have an unintended pregnancy than those who used longer-acting forms such as an intrauterine device (IUD) or implant.

Birth control pills are the most commonly used reversible contraceptive in the United States, but their effectiveness hinges on women remembering to take a pill every day and having easy access to refills. The hormonal IUD is approved for five years, and the copper IUD can be used for as long as 10 years. Hormonal implants are inserted under the skin of the upper arm and are effective for three years. Many women, however, cannot afford or decline to pay the up-front costs of these methods, which can be more than $500.

The study involved over 7,500 women enrolled in the Contraceptive CHOICE project. Participants were between the ages of 14 and 45 and at high risk of unintended pregnancy. The women were either not currently using contraception or wanted to switch birth control methods, and none wished to become pregnant within the next 12 months. The women were counseled about the contraceptive methods, including their effectiveness, side effects, risks, and benefits, and all methods were provided free of charge.

Participants chose among the following birth-control methods: IUD or implant (n=5781), birth control pills, patch, or ring (n=1527), and contraceptive injection (n=176). Overall, there were 334 unintended pregnancies. Of these, 156 were due to contraceptive failure. Overall, 133 (4.55%) women using pills, the patch, or ring had contraceptive failure, compared with 21 (0.27%) women using IUDs and implants.

In age-adjusted analyses, pregnancy risk was significantly higher among women using birth control pills, the patch, or the ring than among those using IUDs or implants (hazard ratio, 21.8). Participants younger than 21 years who used short-acting contraceptives had nearly twice the pregnancy risk as older participants using the same methods, while risk did not differ between age groups for long-acting contraceptives.

Although IUDs are very effective and have been proven safe in women and adolescents, they are chosen by only 5.5% of U.S. women who use contraception.[2] According to the authors, this study may represent a shift in how patients should be counseled about birth control, which could greatly affect unintended pregnancy rates—and can have negative effects on women’s health and education and the health of newborns. The authors also note that when IUDs and implants were provided at no cost, about 75% of the women chose these methods for birth control.

Unintended pregnancy is a major problem in the United States. About 3 million pregnancies per year—50% of all pregnancies—are unplanned.[3] The rate of unintended pregnancy in the United States is much higher than in other developed nations, and past studies have shown that about half of these pregnancies result from contraceptive failure.

 

Jill Shuman, MS, ELS
Published May 24, 2012

 

References

  1. Winner B, Peipert JF, Zhao Q, et al. Effectiveness of long-acting reversible contraception. N Engl J Med. 2012;366:1998-2007. http://www.nejm.org/doi/full/10.1056/NEJMoa1110855?query=featured_home
  2. Mosher WD, Jones J. Use of contraception in the United States: 1982-2008. Vital Health Stat 23. 2010;29:1-44.
  3. Finer LB, Zolna MR. Unintended pregnancy in the United States: incidence and disparities, 2006. Contraception. 2011;84(5):478-485.