Editing Coitus interruptus (section)

== Effects ==
Like many methods of birth control, reliable effect is achieved only by correct and consistent use. Observed failure rates of withdrawal vary depending on the population being studied: American studies have found actual failure rates of 15–28% per year.<ref name="kippley">{{cite book | first1=John | last1=Kippley |first2=Sheila |last2=Kippley | name-list-style = vanc | year=1996 | title=The Art of Natural Family Planning | edition=4th | publisher=The Couple to Couple League | location=Cincinnati | isbn=978-0-926412-13-2 | page=146 }}, which cites:
*{{cite journal | title = Choice of contraceptives | journal = The Medical Letter on Drugs and Therapeutics | volume = 34 | issue = 885 | pages = 111–4 | date = December 1992 | pmid = 1448019 }}
*{{cite book | vauthors=Hatcher RA, Trussel J, Stewart F | display-authors=etal | year=1994 | title=Contraceptive Technology | edition=Sixteenth Revised | publisher=Irvington Publishers | location=New York | isbn=978-0-8290-3171-3 | url-access=registration | url=https://archive.org/details/isbn_9780829031713 | access-date=2019-09-08 | archive-date=2020-08-02 | archive-url=https://web.archive.org/web/20200802203449/https://archive.org/details/isbn_9780829031713 | url-status=live }}</ref> One US study, based on self-reported data from the 2006–2010 cycle of the National Survey of Family Growth, found significant differences in failure rate based on parity status. Women with 0 previous births had a 12-month failure rate of only 8.4%, which then increased to 20.4% for those with 1 prior birth and again to 27.7% for those with 2 or more.<ref>{{cite journal |last1=Sundaram |first1=A |last2=Vaughan |first2=B |last3=Kost |first3=K |last4=Bankole |first4=A |last5=Finer |first5=L |last6=Singh |first6=S |last7=Trussell |first7=J |display-authors= 3 |title=Contraceptive Failure in the United States: Estimates from the 2006–2010 National Survey of Family Growth |journal=Perspectives on Sexual and Reproductive Health |date=March 2017 |volume=49 |issue=1 |pages=7–16 |doi=10.1363/psrh.12017 |pmid=28245088 |pmc=5363251 }}</ref>

An analysis of Demographic and Health Surveys in 43 developing countries between 1990 and 2013 found a median 12-month failure rate across subregions of 13.4%, with a range of 7.8–17.1%. Individual countries within the subregions were even more varied.<ref>{{Cite web |url= https://www.guttmacher.org/report/contraceptive-failure-rates-in-developing-world#|title = Contraceptive Failure Rates in the Developing World: An Analysis of Demographic and Health Survey Data in 43 Countries|date = 24 March 2016|last1 = Polis|first1 = C|last2 = Bradley|first2 = SEK |last3 = Bankole|first3 = A |last4 = Onda|first4 = T |last5 = Croft|first5 = TN |last6 = Singh|first6 = S |display-authors= 3}}</ref> A large scale study of women in England and Scotland during 1968–1974 to determine the efficacy of various contraceptive methods found a failure rate of 6.7 per 100 woman-years of use. This was a “typical use” failure rate, including user failure to use the method correctly.<ref>{{cite journal |last1=Vessey |first1=M |last2=Lawless |first2=M |last3=Yeates |first3=D |title=Efficacy of Different Contraceptive Methods |journal=The Lancet |date=April 1982 |volume= 319 |issue=8276 |pages=841–842 |doi=10.1016/s0140-6736(82)91885-2 |pmid=6122067 |s2cid=24203338 }}</ref> In comparison, the [[combined oral contraceptive pill]] has an actual use failure rate of 2–8%,<ref name="pill">{{cite journal | vauthors = Audet MC, Moreau M, Koltun WD, Waldbaum AS, Shangold G, Fisher AC, Creasy GW | display-authors= 3| title = Evaluation of contraceptive efficacy and cycle control of a transdermal contraceptive patch vs an oral contraceptive: a randomized controlled trial | journal = [[JAMA]] | volume = 285 | issue = 18 | pages = 2347–54 | date = May 2001 | pmid = 11343482 | doi = 10.1001/jama.285.18.2347 | doi-access = free }}<br />
{{cite web | url =http://www.agi-usa.org/pubs/fb_contr_use.html | title =Contraceptive Use | work =Facts in Brief | publisher =[[Guttmacher Institute|The Alan Guttmacher Institute]] | access-date =2005-05-10 | url-status =dead | archive-url =http://webarchive.loc.gov/all/20011218080156/http://www.agi-usa.org/pubs/fb_contr_use.html | archive-date =2001-12-18 }} - see table ''First-Year Contraceptive Failure Rates''</ref> while [[intrauterine device]]s (IUDs) have an actual use failure rate of 0.1–0.8%.<ref name="cont tech 18">{{cite book| url= http://www.contraceptivetechnology.com/table.html|title=Contraceptive Technology|vauthors=Hatcher RA, Trussel J, Stewart F|publisher=Ardent Media| year=2000 |isbn=978-0-9664902-6-8|edition=18th|location=New York|display-authors=etal|access-date=2006-07-13|archive-url= https://web.archive.org/web/20080531095926/http://www.contraceptivetechnology.com/table.html|archive-date=2008-05-31|url-status=dead}}</ref> [[Condom]]s have an actual use failure rate of 10–18%.<ref name="kippley" /> However, some authors suggest that actual effectiveness of withdrawal could be similar to the effectiveness of condoms; this area needs further research.<ref name = "Jones_2009">{{cite journal |last1=Jones |first1=RK |last2=Fennell |first2=J |last3=Higgins |first3=JA |last4=Blanchard |first4=K |title=Better than nothing or savvy risk-reduction practice? The importance of withdrawal |journal=Contraception |date=June 2009 |volume=79 |issue=6 |pages=407–410 |doi=10.1016/j.contraception.2008.12.008 |pmid=19442773 }}</ref> (See [[Comparison of birth control methods]].)

For couples that use ''coitus interruptus'' consistently and correctly at every act of intercourse, the failure rate is 4% per year. This rate is derived from an educated guess based on a modest chance of sperm in the pre-ejaculate.<ref name="Hatcher_2018" /><ref>{{cite journal | vauthors = Trussell TJ, Faden R, Hatcher RA | title = Efficacy information in contraceptive counseling: those little white lies | journal = American Journal of Public Health | volume = 66 | issue = 8 | pages = 761–7 | date = August 1976 | pmid = 961944 | pmc = 1653419 | doi = 10.2105/AJPH.66.8.761 }}</ref> In comparison, the pill has a perfect-use failure rate of 0.3%, IUDs a rate of 0.1–0.6%, and internal condoms a rate of 2%.<ref name="Hatcher_2018" />

It has been suggested that the [[pre-ejaculate]] ("Cowper's fluid") emitted by the penis prior to ejaculation may contain [[Spermatozoon|spermatozoa]] (sperm cells), which would compromise the effectiveness of the method.<ref>{{cite web |first=Roger W. |last=Harms |name-list-style=vanc |title=Can pre-ejaculation fluid cause pregnancy? |work=Women's health: Expert answers |publisher=MayoClinic.com |url=http://www.mayoclinic.com/health/birth-control/an00197 |date=2007-09-20 |access-date=2009-07-15 |archive-date=2009-05-11 |archive-url= https://web.archive.org/web/20090511011612/http://www.mayoclinic.com/health/birth-control/an00197 |url-status=live }}</ref><ref>{{cite web |first=Tracee |last=Cornforth |name-list-style=vanc |title=How effective is withdrawal as a birth control method? |work=About.com: Women's Health |url=http://womenshealth.about.com/cs/birthcontro1/a/withdrawalbircn.htm |date=2003-12-02 |access-date=2009-07-15 |archive-date=2009-02-21 |archive-url=https://web.archive.org/web/20090221074655/http://womenshealth.about.com/cs/birthcontro1/a/withdrawalbircn.htm |url-status=live }}</ref> However, several small studies<ref>{{cite journal | vauthors = Zukerman Z, Weiss DB, Orvieto R | title = Does preejaculatory penile secretion originating from Cowper's gland contain sperm? | journal = Journal of Assisted Reproduction and Genetics | volume = 20 | issue = 4 | pages = 157–9 | date = April 2003 | pmid = 12762415 | pmc = 3455634 | doi = 10.1023/A:1022933320700 }}</ref><ref>{{cite journal | vauthors = Free MJ, Alexander NJ | title = Male contraception without prescription. A reevaluation of the condom and coitus interruptus | journal = Public Health Reports | volume = 91 | issue = 5 | pages = 437–45 | year = 1976 | pmid = 824668 | pmc = 1440560 }}</ref><ref name="HIV study">{{cite journal | title = Researchers find no sperm in pre-ejaculate fluid | journal = Contraceptive Technology Update | volume = 14 | issue = 10 | pages = 154–6 | date = October 1993 | pmid = 12286905 }}</ref><ref name="clark">{{cite journal | vauthors = Clark S | date = September 1981|title=An examination of the sperm content of human pre-ejaculatory fluid | url=http://www.popline.org/node/425048 | archive-url = https://web.archive.org/web/20150924081054/http://www.popline.org/node/425048 | archive-date = 24 September 2015 | journal = Popline | volume = 5| pages = 9–10| publisher = Knowledge for Health Project }}</ref> have failed to find any viable sperm in the fluid. While no large conclusive studies have been done, it is believed by some that the cause of method (correct-use) failure is the pre-ejaculate fluid picking up sperm from a previous ejaculation.<ref name=PP>{{cite web |title=Withdrawal Method |website=[[Planned Parenthood]] |date=March 2004 |url=http://www.plannedparenthood.com/health-topics/birth-control/withdrawal-pull-out-method-4218.htm |access-date=2008-03-28 |archive-date=2008-04-20 |archive-url=https://web.archive.org/web/20080420165238/http://plannedparenthood.com/health-topics/birth-control/withdrawal-pull-out-method-4218.htm |url-status=live }}</ref><ref name="Delvin">{{cite web |last=Delvin |first=David |name-list-style=vanc |title=Coitus interruptus (Withdrawal method) |work=NetDoctor.co.uk |date=2005-01-17 |url=http://www.netdoctor.co.uk/sex_relationships/facts/coitusinterruptus.htm |access-date=2006-07-13 |archive-date=2006-09-24 |archive-url=https://web.archive.org/web/20060924170257/http://www.netdoctor.co.uk/sex_relationships/facts/coitusinterruptus.htm |url-status=live }}</ref> For this reason, it is recommended that the male partner urinate between ejaculations, to clear the urethra of sperm, and wash any ejaculate from objects that might come near the woman's vulva (such as hands and penis).<ref name="Delvin"/>

However, recent research suggests that this might not be accurate. A contrary, yet non-generalizable study that found mixed evidence, including individual cases of a high sperm concentration, was published in March 2011.<ref name="Killick">{{cite journal | vauthors = Killick SR, Leary C, Trussell J, Guthrie KA | title = Sperm content of pre-ejaculatory fluid | journal = Human Fertility | volume = 14 | issue = 1 | pages = 48–52 | date = March 2011 | pmid = 21155689 | pmc = 3564677 | doi = 10.3109/14647273.2010.520798 }}</ref> A noted limitation to these previous studies' findings is that pre-ejaculate samples were analyzed after the critical two-minute point.  That is, looking for motile sperm in small amounts of pre-ejaculate via microscope after two minutes – when the sample has most likely dried – makes examination and evaluation "extremely difficult".<ref name="Killick"/>  Thus, in March 2011 a team of researchers assembled 27 male volunteers and analyzed their pre-ejaculate samples within two minutes after producing them.  The researchers found that 11 of the 27 men (41%) produced pre-ejaculatory samples that contained sperm, and 10 of these samples (37%) contained a "fair amount" of motile sperm (in other words, as few as 1 million to as many as 35 million).<ref name="Killick"/> This study therefore recommends, in order to minimize [[unintended pregnancy]] and disease transmission, the use of condoms from the first moment of genital contact. As a point of reference, a study showed that, of couples who conceived within a year of trying, only 2.5% included a male partner with a total sperm count (per ejaculate) of 23 million sperm or less.<ref>{{cite journal | vauthors = Cooper TG, Noonan E, von Eckardstein S, Auger J, Baker HW, Behre HM, Haugen TB, Kruger T, Wang C, Mbizvo MT, Vogelsong KM | display-authors = 3 | title = World Health Organization reference values for human semen characteristics | journal = Human Reproduction Update | volume = 16 | issue = 3 | pages = 231–45 | year = 2010 | pmid = 19934213 | doi = 10.1093/humupd/dmp048 | doi-access = free }}</ref> However, across a wide range of observed values, total sperm count (as with other identified semen and sperm characteristics) has weak power to predict which couples are at risk of pregnancy.<ref>{{cite journal | vauthors = Slama R, Eustache F, Ducot B, Jensen TK, Jørgensen N, Horte A, Irvine S, Suominen J, Andersen AG, Auger J, Vierula M, Toppari J, Andersen AN, Keiding N, Skakkebaek NE, Spira A, Jouannet P | display-authors = 6 | title = Time to pregnancy and semen parameters: a cross-sectional study among fertile couples from four European cities | journal = Human Reproduction | volume = 17 | issue = 2 | pages = 503–15 | date = February 2002 | pmid = 11821304 | doi = 10.1093/humrep/17.2.503 | doi-access = free }}</ref> Regardless, this study introduced the concept that some men may consistently have sperm in their pre-ejaculate, due to a "leakage," while others may not.<ref name="Killick" />

Similarly, another robust study performed in 2016 found motile sperm in the pre-ejaculate of 16.7% (7/42) healthy men. What more, this study attempted to exclude contamination of sperm from ejaculate by drying the pre-ejaculate specimens to reveal a fern-like pattern, characteristics of true pre-ejaculate. All pre-ejaculate specimens were examined within an hour of production and then dried; all pre-ejaculate specimens were found to be true pre-ejaculate.<ref>{{cite journal | vauthors = Kovavisarach E, Lorthanawanich S, Muangsamran P | title = Presence of Sperm in Pre-Ejaculatory Fluid of Healthy Males | journal = Journal of the Medical Association of Thailand = Chotmaihet Thangphaet | volume = 99 | pages = S38–41 | date = February 2016 | issue = Suppl 2 | pmid = 27266214 }}</ref> It is widely believed that urinating after an ejaculation will flush the urethra of remaining sperm.<ref name=PP/> However, some of the subjects in the March 2011 study who produced sperm in their pre-ejaculate did urinate (sometimes more than once) before producing their sample.<ref name="Killick"/> Therefore, some males can release the pre-ejaculate fluid containing sperm without a previous ejaculation.