Perfect-use failure rates have been documented to be as low as 1.1 per 100 women in the first year of use.18,19
The actual use failure rate for all contraceptive pills (COCs and POPs) reported from the National Survey of Family Growth 2006 to 2010 is 7.2 per 100 women in the first year of use.20
In this cohort, failure rates differ by age (10.4 per 100 women aged 25 to 29 vs. 4.1 per 100 women aged 30 to 44) and by race/ethnicity (13.1 per 100 black women and 6.1 per 100 white women). A systematic review of POPs for contraception did not find statistically significant differences in efficacy between POP types, though the analyses favored desogestrel over levonorgestrel and norethindrone over desogestrel.6
Higher rates of discontinuation were seen with desogestrel due to bleeding irregularities, which likely limited its overall efficacy. There are no published efficacy data comparing
drospirenone POPs with any other formulations. When women are able to adhere to recommended timing of POP administration, the failure rate may be comparable to the rate (<1 per 100 woman-years) with COCs.18
However, use of population data to compare effectiveness of POPs and COCs is limited by selection bias, as users of POPs may have lower fertility risk for a variety of reasons (e.g., age, breastfeeding).