Editing Diaphragm (birth control) (section)

==Mechanism of action==
The spring in the rim of the diaphragm forms a seal against the vaginal walls. The diaphragm covers the [[cervix]], and physically prevents sperm from entering the [[uterus]] through the [[external orifice of the uterus|cervical canal]].

Traditionally, the diaphragm has been used with spermicide, and it is widely believed that the spermicide is a significant factor in the effectiveness of the diaphragm. However, some have asserted that the diaphragm's mechanism of action is primarily as a physical barrier and that a diaphragm is effective without spermicides, but insufficient studies have been conducted to prove this.<ref name=":0" />{{Update inline|reason=Updated version https://www.ncbi.nlm.nih.gov/pubmed/12535422|date = July 2018}}

It is widely taught that additional spermicide must be placed in the vagina if intercourse occurs more than six hours after insertion.<ref name="pp" /><ref name="OrthoPI" />  However, there has been very little research on how long spermicide remains active within the diaphragm. One study found that spermicidal jelly and creme used in a diaphragm retained its full spermicidal activity for twelve hours after placement of the diaphragm.<ref>{{cite journal|author=Leitch W|title=Longevity of Ortho Creme and Gynol II in the contraceptive diaphragm|journal=Contraception|volume=34|issue=4|pages=381–93|year=1986|pmid=3780236|doi=10.1016/0010-7824(86)90090-9}}</ref>

It has long been recommended that the diaphragm be left in place for at least six or eight hours after intercourse. No studies have been done to determine the validity of this recommendation, however, and some medical professionals have suggested intervals of four hours<ref>{{cite journal|author=Kovacs G|title=Fitting a diaphragm| journal=Aust Fam Physician|volume=19|issue=5|pages=713, 716|year=1990|pmid=2346425}}</ref> or even two hours<ref>{{cite journal|author=Bernstein G|title=Is effectiveness of diaphragm compromised by postcoital swimming or bathing?|journal=JAMA|volume=237|issue=3|pages=2643–2644|year=1977|pmid=12259737|doi= 10.1001/jama.237.24.2643}}</ref> are sufficient to ensure efficacy. One manufacturer of [[contraceptive sponge]]s recommends leaving the sponge in place for only two hours after intercourse.<ref name="CBAS">{{cite web|title=Sponges |work=Cervical Barrier Advancement Society |year=2004 |url=http://www.cervicalbarriers.org/information/sponges.cfm |access-date=2006-09-17 |url-status=dead |archive-url=https://web.archive.org/web/20090114062634/http://www.cervicalbarriers.org/information/sponges.cfm |archive-date=2009-01-14 }}</ref> However, such use of the diaphragm (removal before 6 hours post-intercourse) has never been formally studied, and cannot be recommended.

It has been suggested that diaphragms be dispensed as a one-size-fits-all device, providing all women with the most common size (70&nbsp;mm). However, only 33% of women fitted for a diaphragm are prescribed a 70&nbsp;mm size, and correct sizing of the diaphragm is widely considered necessary.<ref>{{cite journal|author=Mauck C |title=Diaphragms in clinical trials: is clinician fitting necessary?|journal=Contraception|volume=69|issue=4|pages=263–6|year=2004|pmid=15033398|doi= 10.1016/j.contraception.2003.11.006|last2=Lai|last3=Schwartz|last4=Weiner}}</ref>