Why Do Women Miss Oral Contraceptive Pills? An Analysis of Women's Self-Described Reasons for Missed Pills

Janice D. Smith, CNM, MS; Deborah Oakley, PhD


J Midwifery Womens Health. 2005;50(5):380-385. 

In This Article

Abstract and Introduction


Inconsistent use of oral contraceptives (OCs) exposes women to risks of unintended pregnancy. This study explored women's self-described reasons for missed OC pills. Data from diary cards completed by 141 women were studied to see how reasons for missing pills were related to patterns of pill use. The findings suggest that practitioners might improve OC use by focusing on the reasons that women miss pills, thus providing a more tailored approach that addresses individual risks based on women's personal experiences.


Oral contraceptives (OCs) are the most popular reversible contraceptive method available in the United States. An estimated 10 to 18 million women currently use OCs.[1] If OC pills are taken perfectly, clinical trial data estimate that less than 1% of new OC users will become pregnant during the first year of use.[2] However, the first-year failure rate from actual use ranges from 3% to 27%, depending on demographic characteristics.[3] In fact, 20% of the 3.5 million annual unintended pregnancies in the United States are estimated to occur after OC pill discontinuation and compliance difficulties.[4]

The reported consistency of OC pill use varies widely among studies.[5,6,7] A retrospective study[8] of 1311 women making initial family-planning visits to metropolitan health department clinics found that only 42% of OC users said they took a pill every day, and only 20% said they took a pill within 2 hours of the same time every day. Another study[9] reported that 19% of a convenience sample of 6676 European women between the ages of 16 and 30 stated they generally miss one or more pills per cycle. Those who reported missing pills were more than three times as likely to experience an unintended pregnancy than were women who took their OCs consistently. Factors associated with poor compliance included a lack of established routine for pill taking, failure to read and understand written material accompanying the OC package, not receiving adequate information from a health care provider, and the occurrence of side effects, such as nausea and bleeding irregularities. More recently, in a study of 992 women who completed questionnaires after 2 months of OC use,[4] 47% of users missed one or more pills per cycle and 22% missed two or more. Women who did not have an established routine for pill taking were nearly four times as likely to miss two or more pills per cycle than were women who did have a routine.

Although providing significant evidence of the prevalence of inconsistent pill use, these studies probably overestimate consistent pill taking. Self-report has been shown to be significantly less reliable than electronic devices that record pill-taking behavior.[10] In a study comparing self-reported data on pill taking with an electronic device measuring compliance among 103 women,[11] the proportion of women reporting no missed pills was much higher than the proportion recorded electronically (53%-59% compared with 19%-33%), and the proportion missing three or more pills according to the electronic data was triple that reported by women in diary records (30%-51% versus 10%-14%). In addition, electronic devices revealed more episodes of consecutive pill misses than did self-reports.

Further understanding of why and when women lapse in taking OCs may enable practitioners to identify interventions for reducing the risk of user-related contraceptive failure. Therefore, the purpose of this study is to analyze OC users' self-described reasons for missing active hormonal pills and to explore whether reasons for missed pills vary according to day of week, times of increased hormonal risk, and consistency of placebo use.

The specific research questions for this study are as follows: 1) What are OC users' self-described reasons for missing active hormonal pills? 2) Is the likelihood of missing consecutive pills (which increases risk of pregnancy) related to the reasons cited for missing pills? 3) Do patterns of use and pregnancy risk differ between weekend days and midweek days? 4) Are users of placebo pills less likely to miss active pills during the rest of their menstrual cycles? and 5) Are usage patterns that increase risk for pregnancy related to users' reasons for missed pills?


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