Source: Trussell, 1994; Jones/Forrest, 1992 (OC typical use data).
Barrier methods can be very effective at preventing pregnancy
when used consistently and correctly. In this slide, the yellow
rectangles on the left show how effective various methods can
be when used both consistently and correctly. If used correctly
at every act of intercourse, barrier methods generally have
low pregnancy rates, about 3 percent for the male condom and
7 percent for spermicides. A 3 percent pregnancy rate means
that three out of every 100 women using this method for a year
would get pregnant.
The red rectangles on the right show how effective the methods
are, based on actual or typical use during one year. Typical
users include those who may not use the method consistently
and correctly. Under typical use, contraceptive pregnancy rates
for some barrier methods are 21 percent or higher. The pregnancy
rates for diaphragms that are used in conjunction with spermicides
are slightly less than those of spermicides when used alone.
Contraceptive effectiveness should improve when the male condom
and vaginally inserted spermicides are used together, although
data on this issue are not available.
Note that the difference between the rates for consistent and
correct use and the rates for typical use is large for certain
methods, such as oral contraceptives and barrier methods. This
is because these methods depend heavily on the client to use
them consistently and correctly. Good counseling may be able
to influence use patterns. Notice also that the difference is
small or non-existent for long-acting methods such as Norplant,
IUDs, Depo-Provera or female sterilization, which do not require
much or any action by the client.
Learner Note: Failure rates
vary from country to country because they are dependent
on many factors. Thus, studies report varying rates,
and it is impossible to calculate one precise rate for
any method. The three main factors that influence the
effectiveness of any contraceptive method include the
inherent effectiveness of the method itself, programmatic
issues, and whether or not the method is used correctly
and consistently by users. Correct use is dependent
not only on the user, but is influenced by a variety
of programmatic factors. To facilitate correct and consistent
use of any contraceptive method, programs must offer
a variety of contraceptive options with adequate counseling
for clients and proper follow-up care. Clients must
also receive complete and instructive information on
how to use the method, and on the importance of correct
and consistent use. Some methods depend greatly on the
technical competence of the provider to administer the
method properly. All methods must also be accessible
and affordable to the user.