Efficiency and Reliability of Methods of Contraception

Barrier Methods

Condoms: These provide around 98% effectiveness with perfect use, but with a typical use it is estimated to be around 85% effective. Also, importantly, they protect against sexually transmitted infections (STIs).
Diaphragm or cap: It is used with spermicide and provides about 92-96% effectiveness with perfect use, but with a typical use it is about 71-88% effective. Note that it does not protect against STIs.
Contraceptive sponge: The effectiveness ranges from 76-88% and doesn’t protect against STIs.

Hormonal Methods

Combined pill: With perfect use, it is around 99.7% effective, but typical use reduces this effectiveness to about 91%. It doesn’t provide protection against STIs.
Progestogen-only pill: Similarly, with perfect use, it is around 99% effective, but it is about 92% effective with typical use. It doesn’t provide protection against STIs.
Contraceptive implant: This is over 99% effective and lasts for up to three years. It doesn’t protect against STIs.
Contraceptive injection: This gives effective contraceptive cover for 8-13 weeks depending on type. It’s over 99% effective with perfect use but around 94% effective with typical use.

Intrauterine Devices (IUDs)

Copper IUD: Once inserted it is more than 99% effective and can last for up to 10 years. It doesn’t protect against STIs.
Hormonal IUD (IUS): Also over 99% effective, it releases progestogen hormone and can last up to 5 years. It doesn’t offer protection against STIs.

Natural Family Planning

This involves identifying the fertile periods in the woman’s menstrual cycle. With perfect use, it can be around 99% effective, but with typical use, effectiveness might be reduced to around 76%.

Emergency Contraception

Morning after pill: Should be taken within 72 hours (the sooner the better) and provides around 85-89% effectiveness. This doesn’t offer any long-term contraceptive cover.
IUD: Can be used as emergency contraceptive within 5 days of unprotected sex or contraceptive failure and is more than 99% effective.

Permanent Methods

Vasectomy: This is an operation to disconnect the sperm transport system. It is over 99% effective upon successful operation.
Female sterilisation: Also a surgical procedure, this method is over 99% effective, but it is not easily reversible.

Remember that “typical use” includes human errors like forgetting to take a pill while “perfect use” means using the contraception correctly and consistently. Also, apart from barrier methods like condoms, most contraceptive methods do not provide protection against STIs.