Contraceptive Effectiveness

A simple chart helps clients understand risks and benefits.

Family Health Research: 2007, Vol. 1, Issue 3

Effectiveness is often the most important consideration when a woman chooses a contraceptive method. But many women do not understand how well various methods protect against pregnancy.

Providers usually explain effectiveness by informing their clients of the pregnancy rates for each method during typical use and during times when it is used consistently and correctly (perfect use). A randomized trial conducted by FHI among 461 U.S. women in 2001, however, found that this level of detail was confusing to many women.

The trial showed that a woman's knowledge of a method's effectiveness was significantly better when the information was presented in a simple chart that describes different contraceptive methods as either "more effective," "less effective," or simply "effective." The trial's participants did not understand the information as well when it was presented in two widely used charts that state the pregnancy rates associated with the methods.

In a follow-up study, FHI researchers worked with colleagues from the World Health Organization (WHO) and the INFO Project at the Johns Hopkins Bloomberg School of Public Health to refine the simplified effectiveness chart. This working group developed three charts depicting the relative effectiveness of contraceptive methods — rather than the pregnancy rates — in different ways.

FHI then compared the three charts in a study among 450 women in India and 450 women in Jamaica. In each country, one-third of the study's participants were randomly assigned to use one of the charts. Each woman was asked two key questions about the relative effectiveness of various contraceptive methods before and after looking at a chart.

Results

In both India and Jamaica, more that half of the study's participants said that their most important reason for choosing a method was how well it prevents pregnancy. Many participants grossly overestimated the risk of pregnancy for a given category of effectiveness before looking at one of the charts.

Each of the three charts helped the participants answer the two questions. The number of women who answered a question correctly increased between 24 percent and 32 percent.

No chart improved knowledge significantly more than another, but the women said they found the simplest chart — which places contraceptive methods on a continuum from least to most effective — slightly easier to understand.

Impact on service delivery

The chart showing a continuum of effectiveness was finalized at a WHO expert working group meeting in June 2005. It appears on the back cover of the new global handbook for family planning providers (you may also download the handbook).

You may download electronic copies of the effectiveness chart and use the chart without permission.