Editing Human sexual activity (section)

==Health and safety==
Sexual activity is an innately physiological function,<ref>Xiaojun Chen, Xuerui Tan, Qingying Zhang, [http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.598.3719 " Cardiovascular effects of sexual activity"] {{Webarchive|url=https://web.archive.org/web/20210629011727/http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.598.3719 |date=29 June 2021 }}, ''Medknow Publications'', December 2009</ref> but like other physical activity, it comes with risks. There are four main types of risks that may arise from sexual activity: [[Unintended pregnancy|unwanted pregnancy]], contracting a [[Sexually transmitted disease|sexually transmitted infection]] (STI), physical injury, and psychological injury.

===Unwanted pregnancy===
{{main|Unintended pregnancy}}
Any sexual activity that involves the introduction of semen into a woman's vagina, such as during sexual intercourse, or contact of semen with her vulva, may result in a pregnancy. To reduce the risk of unintended pregnancies, some people who engage in penile–vaginal sex may use [[birth control|contraception]], such as [[birth control pill]]s, a [[condom]], [[Diaphragm (contraceptive)|diaphragm]]s, [[spermicide]]s, [[hormonal contraception]] or sterilization.<ref name="NOBG">{{Cite book|url=https://books.google.com/books?id=9GclDgAAQBAJ&pg=PA31|title=Netter's Obstetrics and Gynecology E-Book|isbn=978-0323523509|first=Smith|last=Roger P.|date=2017|pages=31–32|publisher=Elsevier Health Sciences }}</ref> The effectiveness of the various contraceptive methods in avoiding pregnancy varies considerably, and depends on the method rather than the user.<ref name="WHCIAPN">{{Cite book|url=https://books.google.com/books?id=8S4oDwAAQBAJ&pg=PA390|title=Women's Health Care in Advanced Practice Nursing, Second Edition|isbn=978-0826190048|publisher=Springer Publishing Company|last1=Alexander|first1=Ivy M.|last2=Johnson-Mallard|first2=Versie|last3=Kostas-Polston|first3=Elizabeth A.|last4=Fogel|first4=Catherine Ingram|last5=Woods|first5=Nancy Fugate|date=2017|page=390}}</ref>

===Sexually transmitted infections===
{{Main|Sexually transmitted infection}}
[[File:Préservatif enroulé.jpg|thumb|right|A rolled-up male [[condom]]]]
Sexual activity that involves skin-to-skin contact, exposure to an infected person's [[bodily fluid]]s or [[mucous membrane]]s<ref>
{{cite web | title = Sexually transmitted infections (STIs) | publisher = World Health Organization | url =https://www.who.int/mediacentre/factsheets/fs110/en/
| access-date = 7 April 2015}}</ref> carries the risk of contracting a sexually transmitted infection. People may not be able to detect that their [[sexual partner]] has one or more STIs, for example if they are asymptomatic (show no symptoms).<ref name="King, B. 2009">King, B. (2009). Human Sexuality Today (Sixth ed.). Upper Saddle River: Pearson Education, Inc.</ref><ref name=Sternak>{{cite journal|last1=Ljubin-Sternak|first1=Suncanica|last2=Mestrovic|first2=Tomislav|title=Review: ''Chlamydia trachonmatis'' and Genital Mycoplasmias: Pathogens with an Impact on Human Reproductive Health|journal=Journal of Pathogens|pages= 183167|date=2014|volume=2014|issue=183167|doi=10.1155/2014/183167|pmid=25614838|pmc=4295611|doi-access=free}}</ref> The risk of STIs can be reduced by [[safe sex]] practices, such as using condoms. Both partners may opt to be tested for STIs before engaging in sex.<ref name="SexInfo STI overview">{{cite web|title=An Overview of STIs|publisher=[[University of California Santa Barbara]] |website= SexInfo Online |access-date=1 October 2013|url=http://www.soc.ucsb.edu/sexinfo/article/overview-stis |date=21 February 2017 |archive-date=4 June 2019|archive-url=https://web.archive.org/web/20190604040017/http://www.soc.ucsb.edu/sexinfo/article/overview-stis|url-status=dead}}</ref> The exchange of body fluids is not necessary to contract an infestation of crab lice. Crab lice typically are found attached to hair in the pubic area but sometimes are found on coarse hair elsewhere on the body (for example, eyebrows, eyelashes, beard, mustache, chest, armpits, etc.). Pubic lice infestations (pthiriasis) are spread through direct contact with someone who is infested with the louse.<ref>{{Cite book|title=Williams gynecology|date=2012|publisher=McGraw-Hill Medical|last1=Hoffman |first1=Barbara L. |last2=Williams |first2=John Whitridge |isbn=9780071716727|edition=2nd|location=New York|oclc=779244257}}</ref><ref>{{citation-attribution|1={{Cite web|url=https://www.cdc.gov/parasites/lice/index.html|title= Lice |website=CDC |language=en-us|access-date=2017-12-04|date=2017-05-02}}}}</ref><ref>{{citation-attribution|1={{Cite web|url=https://www.cdc.gov/parasites/lice/pubic/index.html|title=Lice: Pubic |website=CDC |language=en-us|access-date=2017-12-04|date=2017-05-02}}}}</ref>

Some STIs like [[HIV/AIDS]] can also be contracted by using [[Drug injection|IV drug]] [[Hypodermic needle|needle]]s after their use by an infected person, as well as through childbirth or [[breastfeeding]].<ref name="ECHL">{{Cite book|url=https://books.google.com/books?id=eT58DwAAQBAJ&pg=PA492|title=Essential Concepts for Healthy Living|isbn=978-1284152791|first1=Jeff|last1=Housman|first2=Mary|last2=Odum|date=2017|page=492|publisher=Jones & Bartlett Learning }}</ref>

===Aging===
{{See also|Sexuality in older age}}
Factors such as biological and psychological factors, diseases, mental conditions, boredom with the relationship, and widowhood have been found to contribute to a decrease in sexual interest and activity in old age, but older age does not eliminate the ability to enjoy sexual activity.<ref name="IHONTDOS">{{Cite book|url=https://books.google.com/books?id=JyNkIVdnuBYC&pg=PA196|title=International Handbook on the Demography of Sexuality|isbn=978-9400755123|publisher=Springer Science & Business Media|last=Baumle|first=Amanda K.|date=2013|page=196}}</ref>