Dr
Margaret answers emailers’ embarrassing problems
in this monthly problem page.
Effectiveness
of condoms
Dear
Dr Margaret
How
good are condoms at preventing pregnancy?
You are not the only person who is confused about how
effective condoms actually are for preventing pregnancy
(contraception).
May be you saw the episode of Friends in which Rachel
tells Ross that she is pregnant. Ross was astonished
because
they had used a condom and had had sex only once.
Then he read from the condom package that ‘condoms are
only 97% effective’. In the USA alone, 1.67
million teenagers saw this episode. A survey afterwards
showed
that many of these viewers were worried by it, and
it made them think that condoms were not as reliable
as they had
previously thought.
No
contraceptive is 100% effective (although the Mirena
intrauterine system for women comes close). For
example, research shows that half of all pregnancies
in the
USA are unintended and, of these, half occur to
women who
say they were practising contraception in the month
they conceived.
However,
latex condoms (the most common type) can be a good contraceptive.
If used absolutely correctly,
the failure
rate is about 3% per year. This means that if
100 couples
have regular sex for a year, using condoms correctly
every time, 3 of the women will become pregnant.
This is the
same as the ‘97% effective’ statement
that Ross read on the package.
But
for condoms to be 97% effective, they do have to be used
absolutely correctly. This
means not
damaging it while
removing the foil wrapper, not damaging it
while putting
it on, putting it on the right way round, unrolling
it to its full length, putting it on before
the penis touches
the woman’s genitals and holding it on
after ejaculation. Have a look at our Condoms:
Dos and Don’ts section
for more information.
In
real life, many people do not use condoms as carefully
as they should. This means that
the real-life
failure
rate is, on average, about 9–14% (depending
on which research you believe). So it really
is important to use condoms
properly – their effectiveness depends
to a large extent on you.
Condoms
also provide good protection against sexually transmitted
infections, such as
chlamydia, gonorrhoea
and HIV, but
only if they are used correctly.
Sources
of information
Black K, Kubba A. What’s new in contraception? Trends
in Urology, Gynaecology and Sexual Health 2004;Jan/Feb:22–25.
Collins
RL et al. Entertainment television as a healthy sex educator:
the impact
of condom-efficacy information
in an episode of Friends. Pediatrics 2003;112(5):1115–21.
Gallo
MF et al. Non-latex versus latex male condoms for contraception.
Cochrane
Database
Systematic
Reviews 2003(2):CD003550.
Trussell
J, Vaughan B. Contraceptive failure, method-related discontinuation
and resumption
of use: results
from the 1995 National Survey of
Family Growth. Family
Planning Perspectives 1999;31:64–72.