“Coitus interruptus”的意思、由来-开放百科全书

Coitus interruptus, also known as the rejected sexual intercourse, withdrawal or pull-out method, is a method of birth control in which a man, during sexual intercourse, withdraws his penis from a woman's vagina prior to orgasm (and ejaculation) and then directs his ejaculate (semen) away from the vagina in an effort to avoid insemination.

This method of contraception, widely used for at least two millennia, is still in use today. This method was used by an estimated 38 million couples worldwide in 1991.^[2] Coitus interruptus does not protect against sexually transmitted infections (STIs/STDs).^[3]

History

Perhaps the oldest documentation of the use of the withdrawal method to avoid pregnancy is the story of Onan in the Torah. This text is believed to have been written down over 2,500 years ago.^[4] Societies in the ancient civilizations of Greece and Rome preferred small families and are known to have practiced a variety of birth control methods.^[6]{{rp|12,16–17}} There are references that have led historians to believe withdrawal was sometimes used as birth control.^[5] However, these societies viewed birth control as a woman's responsibility, and the only well-documented contraception methods were female-controlled devices (both possibly effective, such as pessaries, and ineffective, such as amulets).^[6]{{rp|17,23}}

After the decline of the Roman Empire in the 5th century AD, contraceptive practices fell out of use in Europe; the use of contraceptive pessaries, for example, is not documented again until the 15th century. If withdrawal was used during the Roman Empire, knowledge of the practice may have been lost during its decline.^[6]{{rp|33,42}}

From the 18th century until the development of modern methods, withdrawal was one of the most popular methods of birth-control in Europe, North America, and elsewhere.^[5]

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: studies have found actual failure rates of 15–28% per year.^[7] In comparison, the pill has an actual use failure rate of 2–8%,^[8] while the intrauterine device (IUD) has an actual use failure rate of 0.8%.^[13] The condom has an actual use failure rate of 10–18%.^[7] However, some authors suggest that actual effectiveness of withdrawal could be similar to effectiveness of condoms, and this area needs further research.^[9] (See Comparison of birth control methods.)

For couples that use coitus interruptus correctly at every act of intercourse, the failure rate is 4% per year. In comparison, the pill has a perfect-use failure rate of 0.3%, the I.U.D. a rate of 0.6%, and the condom a rate of 2%.^[10]

It has been suggested that the pre-ejaculate ("Cowper's fluid") emitted by the penis prior to ejaculation normally contains spermatozoa (sperm cells), which would compromise the effectiveness of the method.^[11]^[12] However, several small studies^[13]^[14]^[15]^[16] 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.^[17]^[18] 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 (e.g. hands and penis).^[18]

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.^[19] 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."^[19] 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 (i.e. as few as 1 million to as many as 35 million).^[19]

This study therefore recommends, in order to minimise unintended pregnancy and disease transmission, the use of condom 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.^[20]

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.^[21]

It is widely believed that urinating after an ejaculation will flush the urethra of remaining sperm.^[22] Therefore, 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.^[19] Therefore, some males can release the pre-ejaculate fluid containing sperm without a previous ejaculation.

Advantages

The advantage of coitus interruptus is that it can be used by people who have objections to, or do not have access to, other forms of contraception. Some persons prefer it so they can avoid possible adverse effects of hormonal contraceptives or so that they can have a full experience and be able to "feel" their partner.^[23] Other reasons for the popularity of this method are it has no direct monetary cost, requires no artificial devices, has no physical side effects, can be practiced without a prescription or medical consultation, and provides no barriers to stimulation.

Disadvantages

Compared to the other common reversible methods of contraception such as IUDs, hormonal contraceptives, and male condoms, coitus interruptus is less effective at preventing pregnancy.^[10] As a result, it is also less cost-effective than many more effective methods: although the method itself has no direct cost, users have a greater chance of incurring the risks and expenses of either child-birth or abortion. Only models that assume all couples practice perfect use of the method find cost savings associated with the choice of withdrawal as a birth control method.^[24]

The method is largely ineffective in the prevention of sexually transmitted infections (STIs/STDs), like HIV, since pre-ejaculate may carry viral particles or bacteria which may infect the partner if this fluid comes in contact with mucous membranes. However, a reduction in the volume of bodily fluids exchanged during intercourse may reduce the likelihood of disease transmission compared to using no method due to the smaller number of pathogens present.^[15]

Prevalence

Based on data from surveys conducted during the late 1990s, 3% of women of childbearing age worldwide rely on withdrawal as their primary method of contraception. Regional popularity of the method varies widely, from a low of 1% in Africa to 16% in Western Asia.^[25]

In the United States, studies have indicated 56% of women of reproductive age have had a partner use withdrawal. In 2002, only 2.5% were using withdrawal as their primary method of contraception.^[26]

A leading proponent of withdrawal in the mid-19th century was a religious-based "utopian commune" called the Oneida community in New York. To minimize the incidence of pregnancy, teenage males were not permitted to engage in sexual intercourse except with postmenopausal women until they mastered the withdrawal technique.{{citation needed|date=March 2011}}

See also

References

1. ^¹{{cite book|last=Trussell|first=James|year=2011|chapter=Contraceptive efficacy|editor1-last=Hatcher|editor1-first=Robert A.|editor2-last=Trussell|editor2-first=James|editor3-last=Nelson|editor3-first=Anita L.|editor4-last=Cates|editor4-first=Willard Jr.|editor5-last= Kowal|editor5-first=Deborah|editor6-last=Policar|editor6-first=Michael S. (eds.)|title=Contraceptive technology|edition=20th revised|location=New York|publisher=Ardent Media|isbn=978-1-59708-004-0|issn = 0091-9721|oclc=781956734|pages=779–863}} Table 26–1 = Table 3–2 Percentage of women experiencing an unintended pregnancy during the first year of typical use and the first year of perfect use of contraception, and the percentage continuing use at the end of the first year. United States.
2. ^{{cite journal |vauthors=Rogow D, Horowitz S |title=Withdrawal: a review of the literature and an agenda for research |journal=Studies in Family Planning |volume=26 |issue=3 |pages=140–53 |year=1995 |pmid=7570764 |doi=10.2307/2137833 |jstor=2137833}}, which cites:
:Population Action International (1991). "A Guide to Methods of Birth Control." Briefing Paper No. 25, Washington, D. C.
3. ^{{cite journal |author=Creatsas G |title=Sexuality: sexual activity and contraception during adolescence | journal = Curr Opin Obstet Gynecol | volume = 5 | issue = 6 |pages=774–83 |year=1993|pmid = 8286689 | doi=10.1097/00001703-199312000-00011}}
4. ^{{cite web |last=Adams |first=Cecil |authorlink=Cecil Adams |title=Who wrote the Bible? (Part 1) |work=The Straight Dope|publisher=Creative Loafing Media, Inc. |date=2002-01-07 |url=http://www.straightdope.com/columns/read/1985/who-wrote-the-bible-part-1 |accessdate=2009-07-24}}
5. ^¹{{cite book |author=Bullough, Vern L. |title=Encyclopedia of birth control |publisher=ABC-CLIO |location=Santa Barbara, Calif |year=2001 |pages=74–75 |isbn=978-1-57607-181-6 |url=https://books.google.com/books?id=XuX-MGTZnJoC&pg=PA74&lpg=PA74 |accessdate=2009-07-24}}
6. ^¹²{{cite book | first=Aine | last=Collier | year=2007 | title=The Humble Little Condom: A History | publisher=Prometheus Books | location=Amherst, NY | isbn=978-1-59102-556-6}}
7. ^¹{{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, OH | isbn=978-0-926412-13-2 | pages=146 }}, which cites:
:{{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 }}
{{cite book | first=RA | last=Hatcher |author2=Trussel J|author3=Stewart F| year=1994 | title=Contraceptive Technology | edition=Sixteenth Revised | publisher=Irvington Publishers | location=New York | isbn=978-0-8290-3171-3 |display-authors=etal}}
8. ^{{cite journal | vauthors=Audet MC, Moreau M, Koltun WD, Waldbaum AS, Shangold G, Fisher AC, Creasy GW | title=Evaluation of contraceptive efficacy and cycle control of a transdermal contraceptive patch vs an oral contraceptive: a randomized controlled trial | journal=JAMA | year=2001 | pages=2347–54 | volume=285 | issue=18 | pmid=11343482 | url=http://www.contraceptiononline.org/slides/slide01.cfm?q=pearl+index&dpg=6 | format=Slides of comparative efficacy] | doi=10.1001/jama.285.18.2347 }}
{{cite web | author =Guttmacher Institute | authorlink =Guttmacher Institute | url =http://www.agi-usa.org/pubs/fb_contr_use.html | title =Contraceptive Use | work =Facts in Brief | publisher =Guttmacher Institute | accessdate =2005-05-10 | deadurl =yes | archiveurl =http://webarchive.loc.gov/all/20011218080156/http://www.agi-usa.org/pubs/fb_contr_use.html | archivedate =2001-12-18 | df = }} - see table First-Year Contraceptive Failure Rates
9. ^{{cite journal |vauthors=Jones RK, Fennell J, Higgins JA, Blanchard K |title=Better than nothing or savvy risk-reduction practice? The importance of withdrawal |journal=Contraception |volume=79 |issue=6 |pages=407–10 |date=June 2009 |pmid=19442773 |doi=10.1016/j.contraception.2008.12.008 |url=http://www.guttmacher.org/pubs/journals/reprints/Contraception79-407-410.pdf |accessdate=2009-07-23 }}
10. ^¹²{{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}}
11. ^{{cite web |first=Roger W. |last=Harms |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 |accessdate=2009-07-15 }}
12. ^{{cite web |first=Tracee |last=Cornforth |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 |accessdate=2009-07-15 }}
13. ^{{cite journal |last=Zukerman |first=Z. |title=Short Communication: Does Preejaculatory Penile Secretion Originating from Cowper's Gland Contain Sperm? | journal = Journal of Assisted Reproduction and Genetics | volume = 20 | issue = 4 |pages=157–159 |date=April 2003 | pmid = 12762415 | doi = 10.1023/A:1022933320700 |last2=Weiss |first2=DB |last3=Orvieto |first3=R | pmc=3455634}}
14. ^{{cite journal |vauthors=Free M, Alexander N |title=Male contraception without prescription. A reevaluation of the condom and coitus interruptus |journal=Public Health Rep |volume=91 |issue=5 |pages=437–45 |year=1976 |pmid=824668|pmc=1440560}}
15. ^¹{{cite journal |title=Researchers find no sperm in pre-ejaculate fluid | journal = Contraceptive Technology Update | volume = 14 | issue = 10 |pages=154–156 |date=October 1993 | pmid = 12286905 }}
16. ^{{cite web|author=Clark, S.|year=Sep 1981|title=An examination of the sperm content of human pre-ejaculatory fluid|publisher=[Unpublished]|url=http://www.popline.org/node/425048}}
17. ^{{cite web |title=Withdrawal Method |publisher=Planned Parenthood |date=March 2004 | url =http://www.plannedparenthood.com/health-topics/birth-control/withdrawal-pull-out-method-4218.htm |accessdate=2008-03-28 }}
18. ^¹{{cite web |last=Delvin |first=David |title=Coitus interruptus (Withdrawal method) |work=NetDoctor.co.uk |date=2005-01-17 |url=http://www.netdoctor.co.uk/sex_relationships/facts/coitusinterruptus.htm |accessdate=2006-07-13 }}
19. ^¹²³{{Cite journal|vauthors=Killick SR, Leary C, Trussell J, Guthrie KA |doi=10.3109/14647273.2010.520798|year=2011|title=Sperm content of pre-ejaculatory fluid|journal=Human Fertility|volume=14|issue=1|pages=48–52|pmid=21155689|pmc=3564677}}
20. ^{{cite journal|last=Cooper|first=T.G. |author2=Noonan, E. |author3=von Eckaedstein, S. |author4=Auger, J. |author5=Baker, H.W.G. |author6=Behre, H.M. |title=World Health Organisation reference values for human semen characteristics|journal=Human Reproduction Update|year=2010|volume=16|pages=231–245|doi=10.1093/humupd/dmp048|pmid=19934213|issue=3|display-authors=etal}}
21. ^{{cite journal|last=Slama|first=R.|author2=Eustache, F.|title=Time to pregnancy and semen parameters: a cross-sectional study among fertile couples from four European cities|journal=Human Reproduction|year=2002|volume=17|pages=503–15|issue=2|doi=10.1093/humrep/17.2.503|display-authors=etal|pmid=11821304}}
22. ^{{Cite web| title = Withdrawal Method | work = Planned Parenthood |date=March 2004 | url =http://www.plannedparenthood.com/health-topics/birth-control/withdrawal-pull-out-method-4218.htm | accessdate = 2006-09-01 }}
23. ^{{cite journal|author=Ortayli, N|title=Why Withdrawal? Why not withdrawal? Men's perspectives|journal=Reproductive Health Matters|year=2005|volume=13|issue=25|pages=164–73|pmid=16035610|doi=10.1016/S0968-8080(05)25175-3|last2=Bulut|first2=A|last3=Ozugurlu|first3=M|last4=Cokar|first4=M}}
24. ^{{cite journal|journal = American Journal of Public Health|title=The economic value of contraception: a comparison of 15 methods|author = James Trusell|date = April 1995|volume = 85|issue = 4|pages= 494–503|url=http://www.ajph.org/cgi/reprint/85/4/494.pdf|doi = 10.2105/AJPH.85.4.494|pmid = 7702112|last2 = Leveque|first2 = JA|last3 = Koenig|first3 = JD|last4 = London|first4 = R|last5 = Borden|first5 = S|last6 = Henneberry|first6 = J|last7 = Laguardia|first7 = KD|last8 = Stewart|first8 = F|last9 = Wilson|first9 = TG| displayauthors = 8|pmc = 1615115}}
25. ^{{cite journal |title=Family Planning Worldwide: 2002 Data Sheet |publisher=Population Reference Bureau |year=2002 |url=http://www.prb.org/pdf/FamPlanWorldwide_Eng.pdf |accessdate=2006-09-14 }}
26. ^{{cite journal |last1=Chandra |first1=A |last2=Martinez |first2=GM |last3=Mosher |first3=WD |last4=Abma |first4=JC |last5=Jones |first5=J |title=Fertility, Family Planning, and Reproductive Health of U.S. Women: Data From the 2002 National Survey of Family Growth |publisher=National Center for Health Statistics | journal = Vital and Health Statistics | volume = 23 | issue = 25 |year=2005 |url=https://www.cdc.gov/nchs/data/series/sr_23/sr23_025.pdf |accessdate=2007-05-20 }} See Tables 53 and 56.