Use of levonorgestrel emergency contraception in Utah: is it more than "plan B"?

It is important to understand why some women use levonorgestrel emergency contraceptive pills repeatedly, because the method is not intended for repeated use, and current evidence suggests that it is approximately 77% effective at preventing pregnancy.

An anonymous patient survey of 1,040 women aged 18-29 purchasing levonorgestrel at Planned Parenthood clinics in Utah was conducted during a 4-6-week period in 2007. Chi-square tests and analyses of variance were used to examine associations between selected characteristics and level of levonorgestrel use. Logistic regression was used to assess characteristics independently associated with repeated use.

Twenty-nine percent of participants had used levonorgestrel more than twice in the prior year. Fifty-eight percent believed that levonorgestrel is at least 90% effective in protecting against pregnancy; 16% believed that it is 100% effective. In univariate analyses, lifetime number of partners, currently having multiple partners, substance use at last intercourse and perceived effectiveness of levonorgestrel were positively associated with repeated levonorgestrel use in the previous year. The measure most strongly associated with repeated levonorgestrel use in multivariate analyses was perceived effectiveness: Women who believed that the method is 90-99% or 100% effective in preventing pregnancy had greater odds of repeated use than those who believed it is 75-89% effective (odds ratios, 1.8 each).

Women who repeatedly use levonorgestrel may have an inflated perception of its effectiveness. Future research, including qualitative research, may help clarify factors that lead to inflated perceptions of effectiveness.