Research from Three Developing Countries Confirms Hierarchy of Contraceptive Effectiveness

Results from a recent analysis supported by USAID and the National Institutes of Health underscore the counseling message that when it comes to preventing pregnancy, injectable contraceptives are more effective than combined oral contraceptive pills, which are more effective than condoms. The analysis was conducted by scientists at Family Health International, Makere University in Uganda, the University of Zimbabwe, and Chiang Mai University in Thailand, and was based on data collected between November 1999 and January 2004.

The research involved 5,224 women from Uganda, Zimbabwe, and Thailand who had participated in a study on the association between hormonal contraception and HIV acquisition. Results showed that for a woman using an injectable contraceptive, the risk that she would become pregnant within one year of starting the method was 1 percent or less in all three countries. In Uganda and Zimbabwe, the risk that a user of oral contraceptive pills would become pregnant was at least 10 percent. 

For women intending to use injectables, pills, or condoms at the beginning of the study, the annual pregnancy risk for condoms was by far the highest: as high as 30 percent in Uganda. The risk of pregnancy among users of pills or condoms was substantially lower in Thailand than in the African countries, but the investigators were not able to clarify the reason for this discrepancy.

Study investigators support contraceptive counseling that clarifies the different levels of pregnancy protection afforded by different methods, and that informs women that their experience with a particular form of contraception may vary from the average or typical experience. Furthermore, the investigators urge counselors to provide women with tailored counseling, to allow them to make more informed contraceptive choices.

To read more about this topic, click here.  Also see FHI's contraceptive effectiveness chart.

Sources
Steiner MJ, et al. Pregnancy risk among oral contraceptive pill, injectable contraceptive, and condom users in Uganda, Zimbabwe, and Thailand. Obstet Gynecol 2007;110(5):1003–1009.