Oral contraceptive use and protective behavior after missed pills

Abstract

A three-month prospective study of 103 women initiating oral contraceptive use examined how consistently the women took their pills and whether those who missed pills employed other means to avoid pregnancy. The results showed that 52% took each active pill or never missed more than one pill at a time after the first week of the initial cycle, according to electronic devices that recorded the date and time each pill was removed from the blister pack. Another 21% were protected by behaviors that reduce the risk of pregnancy when two or more consecutive pills have been missed: avoiding coitus for the next seven days (18%) or using backup contraception during that period (3%). The remaining 27% were at increased risk of pregnancy. Predictors of increased risk were receiving low partner support for effective pill use, being unmarried and not considering it especially important to avoid pregnancy. Increased risk was most likely during the first seven days and during the third cycle of pill use.

PIP: User compliance with oral contraceptives (OCs) and protective behaviors after missed pills were investigated in a 3-month prospective study of 103 new OC users recruited from university student health services and Title X-funded clinics in Michigan and North Carolina (US) in 1993-94. Pill usage was verified through a microchip in the OC dispenser that recorded the date and time each pill was pushed out of the blister pack. The electronic records indicated that 51 women never missed a pill in the 3-month study period, while 52 women had a total of 93 missed pill episodes. Overall, 73% were protected against an increased risk of pregnancy throughout the study: 52% by OC use alone, 18% because they never had intercourse during the 7 days after a missed pill episode, and 3% because they used backup contraception in those 7 days. Protection from pills alone decreased from 85% in cycle 1 to 61% in cycle 3. Multivariate analysis indicated that women who had ever been at risk of pregnancy during the study period had coitus an average of 22 days compared with 11 days among those never at risk. In addition, women at risk were more likely to have had unprotected sex during the first 7 days of the study and during cycle 3. Finally, the analysis indicated the risk of unprotected days was significantly elevated in 3 groups of women: those with a lower level of perceived partner support for effective OC use, unmarried women, and those who considered it not especially important to avoid pregnancy now. Clinicians need to provide individualized care aimed at maximizing women's ability to identify and solve likely problems associated with their contraceptive method choice. Emergency contraception should be considered as a last resort for occasional lapses in pill taking.