Editing Diaphragm (birth control) (section)

===Effectiveness===
The effectiveness of diaphragms, as of most forms of [[contraception]], can be assessed two ways: ''method effectiveness'' and ''actual effectiveness''.  The method effectiveness is the proportion of couples correctly and consistently using the method who do not become pregnant. Actual effectiveness is the proportion of couples who intended that method as their sole form of birth control and do not become pregnant; it includes couples who sometimes use the method incorrectly, or sometimes not at all. Rates are generally presented for the first year of use. Most commonly the [[Pearl Index]] is used to calculate effectiveness rates, but some studies use [[decrement table]]s.

For all forms of contraception, actual effectiveness is lower than method effectiveness, due to several factors:

* mistakes on the part of those providing instructions on how to use the method
* mistakes on the part of the method's users
* conscious user non-compliance with method

For instance, someone using a diaphragm might be fitted incorrectly by a health care provider, or by mistake remove the diaphragm too soon after intercourse, or simply choose to have intercourse without placing the diaphragm.

''Contraceptive Technology'' reports that the method failure rate of the diaphragm with spermicide is 6% per year.<ref name="hatcher">{{cite book|first=RA|last=Hatcher|author2=Trussel J|author3=Stewart F|year=2000|title=Contraceptive Technology|edition=18th|publisher=Ardent Media|location=New York|isbn=978-0-9664902-6-8|url=http://www.contraceptivetechnology.com/table.html|display-authors=etal|url-status=live|archive-url=https://web.archive.org/web/20080531095926/http://www.contraceptivetechnology.com/table.html|archive-date=2008-05-31}}</ref>

The actual pregnancy rates among diaphragm users vary depending on the population being studied, with yearly rates of 10%<ref>{{cite journal|author1=Bulut A |title=Assessing the acceptability, service delivery requirements, and use-effectiveness of the diaphragm in Colombia, Philippines, and Turkey|journal=Contraception|volume=63|issue=5|pages=267–75|year=2001|pmid=11448468| doi=10.1016/S0010-7824(01)00204-9|last2=Ortayli|last3=Ringheim|last4=Cottingham|last5=Farley|last6=Peregoudov|last7=Joanis|last8=Palmore|last9=Brady|last10=Diaz|last11=Ojeda|last12=Ramos}}</ref> to 39%<ref>{{cite book|first=John|last=Kippley|author2=Sheila Kippley|year=1996|title=The Art of Natural Family Planning|edition=4th addition|publisher=The Couple to Couple League|location=Cincinnati, Ohio|isbn=978-0-926412-13-2|pages=146}}, which cites:<br>
:{{cite journal|last=Guttmacher Institute|title=Choice of Contraceptives|journal=The Medical Letter on Drugs and Therapeutics|volume=34|pages=111–114|year=1992|pmid= 1448019|issue=885}}</ref> being reported.

Unlike some other cervical barriers, the effectiveness of the diaphragm is the same for women who have given birth as for those who have not.<ref>{{cite journal| author1=Trussell J |author2=Strickler J |author3=Vaughan B|title=Contraceptive efficacy of the diaphragm, the sponge and the cervical cap|journal=Fam Plann Perspect|volume=25|issue=3| pages=100–5, 135|year=1993|pmid=8354373|doi=10.2307/2136156|jstor=2136156 }}</ref>