- How a method works and how to use it;
- Whether a method is physically safe for her health;
- How effective the method is in preventing pregnancy;
- Whether a method protects her and her partner against contracting a Sexually Transmitted Infection (STI).
Cervical Cap 86-92%
Depo Provera 97-99%
Emergency Contraception No effectiveness is given (not a continuous method of birth control)
Evra Patch 92-99%
*Effectiveness data obtained from Contraceptive Technology 19th Revised Edition, Hatcher el (New York: 2007),
The lower rate listed above in the actual percent of women using the method, or actual use. The upper rate is the theoretical effectiveness, based on mathematical formulas.
Actual use takes into account the failure of the contraceptive to work, difficulties with use, and other factors (e.g., women on hormonal birth control are more likely to have a failure when taking antibiotics).
It is helpful to remember that without using any birth control method; approximately 850 women out of 1000 will become pregnant. More information about problems with birth control usage, unprotected sex, and what is available to women please go to our section on Emergency Contraception.