Effectiveness of contraconceptives
The ability of a contraceptive method to prevent gestation (sometimes called, incorrectly, safety) is expressed by the called Pearl Index, which indicates the number of pregnancies that would present, theoretically, 100 women who used this method for a year. This index may be imprecise, since the effectiveness of some methods in the first year is less than in successive years.
That is why, in the studies of new contraceptive techniques is usually used the table of life , which establishes cumulative failure rates for specified periods of time, and that also contemplates the dropout rate. We must also emphasize the difference between the theoretical efficiency which would represent a method used under the optimum technical conditions, and the effectiveness : the one that results in the moment of its implantation and is conditioned by possible human failures. Thus, we call "ideal use or perfect use" as the correct and consistent use of the contraceptive method, without interruptions and without intervening factors that could affect performance of the method, and "typical use" as the use that the individual gives to his contraceptive method, and is susceptible to human error or failure of the method, either by lack of information, method limitations, poor memory, errors of use, interference of other factors on the method, etc.
Safety of a contraceptive
is the ability of a method to alter positive or negatively the health of the user, or threaten his life. To study this parameter, cross-sectional studies, case-control studies, cohort, clinical trials, etc. were made.
Reversibility of a contraceptive
It values the recovery of the reproductive capacity to the interrupt the use of a particular method.
Complexity of use of a contraceptive
For potential users of contraceptives, non-literate, or unaccustomed to calendar representing the blister, or not having manual ability to place a diaphragm for example.
Relation with intercourse
Three types of methods can be distinguished. Which have immediate, mediate and distant relationship.
- Immediate relationship: intercourse interrupted, condom.
- Mediate relationship : diaphragm, vaginal sponge and spermicides.
- Distant relationship : sterilization, IUD and hormonal contraception.
Price
Can influence the choice of the user. Not all methods are covered by Social Security. Also collective as adolescents, with less economic resources, prostitutes (the female condom has a Price superior to the masculine), etc, can be seen very influenced by the cost of the contraceptive method.