Contraception failure rates per method

[REP]

19. These studies show they are used correctly more often than not

As one poster mentioned above, antibiotics that lessen the effectiveness of oral BC are often dispensed without the patient being advised to use a back-up method during therapy - this isn't really "user error" unless the user is a pharmacist. Cervical caps, sponges, etc have different effective rates in women who given birth and women who haven't due to the changes in the cervix - this is more of a product design error (they should come in two sizes at least). The Depo shot stays in the system for 10 months after the last one (it takes that before normal endometrial function resumes), so being a day or week late with a shot really won't cause a disruption in the protection.

But aside from that, as the saying goes, "there was one perfect person and he died 2,000 years ago ..."