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


There were 372 total reported instances of missed pills. Ninety-six of the 141 women (68.1%) included in the study reported missing one or more pills, and 48.9% of participants reported missing two or more pills at some point during the 3-month study period. The range of cumulative misses for individual women was from one missed pill to 27 missed pills over the 3-month study period; the majority of women missed four pills or fewer.

The 3 most frequent reasons cited by participants for missing pills were "away from home" (12.9%), "forgot" (12.9%), and "no new pack" (10.5%) ( Table 2 ). "Health" and "side effects" were the least likely to be cited. Health problems, such as nausea and vomiting, accounted for only 2.4% of missed pill instances, whereas side effects were cited as the reason for a missed pill only five times (1.3%) out of the 372 total instances of missed pills.

There was a statistically significant relationship between reasons for missed pills and missing pills consecutively (P < .001; Table 3 ). There were a total of 119 consecutive misses (32.0% of the total misses). One missed pill day was more likely to be followed by another if "unavailable" was given as the reason for missing pills (44.3%). Note that if the reason for missing pills was physiologic, the likelihood that pills were missed on consecutive days was only 10.7%. Women missed pills on consecutive days in a significant proportion of the instances in which "work pressures" and "no new pill pack" were cited as the reason for a missed pill (19.3% and 21.9%, respectively).

Whether pills were missed on the weekend versus midweek was not significantly related to increased pregnancy risk (P = .54) but was marginally related to the incidence of consecutive misses (P = .09) and reasons provided for missing pills (P = .08; data not shown). Controlling for the fact that there are only 3 weekend days (Friday, Saturday, or Sunday) while there are 4 midweek days (Monday through Thursday), it was no more likely that the missed pill event occurred on one of the weekend days than on one of the weekdays. It is interesting to note, however, that "unavailable" was more likely to be the reason for missed pills on weekend days (57.4%), whereas "other" and "physiologic" were more often cited on weekdays. More specifically, instances of missed pills due to being "away from home," "late start," having "no new pack," "side effects," and "travel" occurred more frequently on weekends.

There was no statistically significant relationship between the reasons participants gave for missing a pill and whether they took placebo pills that cycle (P > .05; data not shown). Analysis of variance was used to test whether women who took pills correctly (i.e., missed few pills and followed directions in the event of a missed pill) were more likely to take placebo pills consistently. Neither the percentage of days in which participants missed pills nor the percentage of pill misses followed by two pills the next day predicted consistent placebo use (P > .05). However, 44.8% of participants in this study reported taking placebo pills inconsistently. In other words, some days they took a placebo pill and other days they did not.

There was a significant relationship between reasons given for missed pills and taking 2 pills the day after missed pills (P < .01; Table 3 ). Although the majority of women did take two pills the next day, 35.8% of women did not. In 14 instances (3.8% of the total instances of missed pills), it was unknown whether two pills were taken the day after a pill miss. Taking two pills the day after a pill miss was more likely when a physical reason had been cited as the reason for missing pills (82.1%) and slightly less likely when "other" and "unavailable" were cited as reasons (58.1% and 59.8%, respectively). Two pills were not taken the day after the initial pill miss in 69% of instances due to "no new pill pack," 60% of instances due to "side effects," and 73% of instances due to "work pressures."

Finally, reasons given for missed pills were significantly related to increased pregnancy risk as defined for this study (P < .01; Table 3 ). Approximately 21% (77 of 372) of missed pill incidences were consecutive pill misses, were not made up the next day, and were not self-described as late in the diary cards, thus placing the user at an increased risk for pregnancy. Missed pills were much more likely to contribute to an increased risk of pregnancy when "unavailable" was given as the reason for missed pills (30.3%). In contrast, an associated increase in pregnancy risk was less likely when "physiologic" and "other" reasons were given (10.7% and 16.7%, respectively).


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