What is the most effective form of contraception?

To determine the effectiveness of different forms of contraception, it is essential to consider their failure rates and how consistently they are used. Oral contraception, while highly effective when taken correctly, requires daily adherence and may have varying effectiveness depending on additional factors like drug interactions and gastrointestinal disturbances.

Intrauterine devices (IUDs) rank as one of the most effective long-term contraceptive methods, with failure rates less than 1%. They provide a "set it and forget it" approach, reducing the reliance on daily user compliance seen with oral contraception. IUDs can remain effective for several years, depending on the type, and provide high efficacy due to their mechanism of action, which includes preventing fertilization and possibly altering the uterine lining.

Barrier methods, while useful, generally have higher failure rates than IUDs and oral contraception, particularly when not used consistently or correctly. Emergency contraception is designed for short-term use after unprotected intercourse and is not meant for regular contraceptive use.

Thus, while oral contraception can be effective, Intrauterine devices are regarded as the most effective form of contraception overall due to their low failure rates, ease of use once placed, and long-term effectiveness.