THEORETICAL AND ACTUAL FALURE RATES OF STERILISATION
AND REVERSIBLE BIRTH CONTROL METHODS

Theoretical failure rate of 100 typical users who start out the year
employing a given method, the theoretical failure rate is the number who
will be pregnant at the end of the year.

Actual failure rate of 100 women who start out the year using a given
method, and who use it correctly and consistently, the actual failure
rate is the lowest observed failure rate.


                                        Theoretical Failure     Actual Failure 
                                        Rate                    Rate

Tubal Ligation                          .04                     .04

Vasectomy                               .15                     .15

Injectible Progestin                    .25                     .25

Combined Birth Control Pills            .5                      2

Progestin Only Birth Control Pills      1.0                     2.5

Condom and Foam                         1.0                     2

IUD                                     1.5                     4

Condom                                  2                       10

Diaphragm and Jelly                     2                       10

Cervical Cap                            2                       13

Foam, Creams, Jellies, Suppositories    3 - 5                   15

Mucus Observation                       .1 - 5.7                2.3 - 39.7

Sympto-thermal Method                   .5 - 13.1               4.5 - 34.4

Source:  ~Contraceptive Techonology, 1982-1983~, 11th rev. ed., (New York: 
Irvington Publishers, 1982), p. 112