**3.4 Effectiveness**

The effectiveness of POPs in preventing pregnancy is as high as that of combined estrogen-progestin contraceptive pills; moreover, intake delay of up to 12 h does not affect contraceptive efficacy [57]. Nevertheless, the effectiveness of this method still depends on the user, as higher failure rates occur with poor compliance. For perfect users, the failure rate is <1 pregnancy per 100 women over the first year (3 per 1000 women). However, for typical users, the failure rate is 1 pregnancy per 100 women in the first year for breastfeeding women and 3–10 pregnancies per 100 women in the first year for non-breastfeeding women [58].
