Editing Infertility (section)

{{Short description|Inability to reproduce}}
{{Use dmy dates|date=March 2021}}
{{Infobox medical condition (new)
| name = Infertility
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| field = [[Urology]], [[gynecology]]
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| causes = Common in females: anovulation, blocked fallopian tube, hormonal imbalance <br /> Common in males: [[Oligospermia|low sperm count]], abnormal sperm morphology
| risks = 
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| frequency = 113 million (2015)<ref name=GBD2015Pre>{{cite journal | vauthors = Vos T, Allen C, Arora M, Barber RM, Bhutta ZA, Brown A, etal | collaboration = GBD 2015 Disease and Injury Incidence and Prevalence Collaborators | title = Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015 | journal = Lancet | volume = 388 | issue = 10053 | pages = 1545–1602 | date = October 2016 | pmid = 27733282 | pmc = 5055577 | doi = 10.1016/S0140-6736(16)31678-6 }}</ref>
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In biology, '''infertility''' is the inability of a male and female organism to [[Sexual reproduction|reproduce]]. It is usually not the natural state of a healthy organism that has reached [[sexual maturity]], so [[children]] who have not undergone [[puberty]], which is the body's start of [[fertility|reproductive capacity]], are excluded. It is also a normal state in women after [[menopause]].

In humans, ''infertility'' is defined as the inability to become [[pregnant]] after at least one year of unprotected and regular [[sexual intercourse]] involving a male and female partner.<ref name="Carson 2021">{{cite journal |last1=Carson |first1=Sandra Ann |last2=Kallen |first2=Amanda N. |title=Diagnosis and Management of Infertility: A Review |journal=JAMA |date=6 July 2021 |volume=326 |issue=1 |pages=65–76 |doi=10.1001/jama.2021.4788|pmid=34228062 |pmc=9302705 }}</ref> There are many causes of infertility, including some that [[Assisted reproductive technology|medical intervention]] can treat.<ref name=pmid14569805>{{cite journal | vauthors = Makar RS, Toth TL | title = The evaluation of infertility | journal = American Journal of Clinical Pathology | volume = 117 | issue = Suppl | pages = S95-103 | date = June 2002 | pmid = 14569805 | doi = 10.1309/w8lj-k377-dhra-cp0b }}</ref> Estimates from 1997 suggest that worldwide about five percent of all heterosexual couples have an unresolved problem with infertility. Many more couples, however, experience involuntary childlessness for at least one year, with estimates ranging from 12% to 28%.<ref>{{cite journal | vauthors = Himmel W, Ittner E, Kochen MM, Michelmann HW, Hinney B, Reuter M, Kallerhoff M, Ringert RH | display-authors = 6 | title = Management of involuntary childlessness | journal = The British Journal of General Practice | volume = 47 | issue = 415 | pages = 111–118 | date = February 1997 | pmid = 9101672 | pmc = 1312893 }}</ref>

[[Male infertility]] is responsible for 20–30% of infertility cases, while 20–35% are due to [[female infertility]], and 25–40% are due to combined problems in both partners.<ref name=eshre2014>{{cite web|url=https://www.eshre.eu/guidelines-and-legal/art-fact-sheet.aspx|title=ART fact sheet (July 2014)|website=[[European Society of Human Reproduction and Embryology]]|url-status=dead|archive-url=https://web.archive.org/web/20160304060954/https://www.eshre.eu/Guidelines-and-Legal/ART-fact-sheet.aspx|archive-date=4 March 2016}}</ref> In 10–20% of cases, no cause is found.<ref name=eshre2014/> 

The most common causes of female infertility are hormonal in nature, including low [[estrogen]], imbalanced [[GnRH]] secretion, [[PCOS]], and aging, which generally manifests in sparse or absent menstrual periods leading up to menopause.<ref name="Walker" /><ref name="Causes of infertility">{{cite web|url=http://www.nhs.uk/Conditions/Infertility/Pages/causes.aspx|title=Causes of infertility|website=[[National Health Service]]|date=2017-10-23|access-date=21 February 2016|archive-date=29 February 2016|archive-url=https://web.archive.org/web/20160229143114/http://www.nhs.uk/Conditions/Infertility/Pages/Causes.aspx|url-status=live}} Page last reviewed 15 July 2014</ref> As women age, the number of [[ovarian follicles]] and [[oocytes]] (eggs) decline, leading to a reduced ovarian reserve.<ref name="Carson 2021" /> Some women undergo [[primary ovarian insufficiency]] (also known as premature menopause) or the loss of ovarian function before age 40, leading to infertility.<ref name="Stuenkel 2023">{{cite journal |last1=Stuenkel |first1=Cynthia A. |last2=Gompel |first2=Anne |title=Primary Ovarian Insufficiency |journal=New England Journal of Medicine |date=12 January 2023 |volume=388 |issue=2 |pages=154–163 |doi=10.1056/NEJMcp2116488|pmid=36630623 }}</ref> 85% of infertile couples have an identifiable cause and 15% is designated unexplained infertility.<ref name="Carson 2021" /> Of the 85% of identified infertility, 25% is due to disordered ovulation (of which 70% of the cases are due to [[polycystic ovarian syndrome]]).<ref name="Carson 2021" /> Tubal infertility, in which there is a structural problem with the [[fallopian tubes]] is responsible for 11-67% of infertility in women of childbearing age, with the large range in prevalence due to different populations studied.<ref name="Carson 2021" /> [[Endometriosis]], the presence of [[endometrium|endometrial tissue]] (which normally lines the uterus) outside of the uterus, accounts for 25-40% of female infertility.<ref name="Carson 2021" />

Women who are [[Fertility#Human fertility|fertile]] experience a period of fertility before and during [[ovulation]], and are infertile for the rest of the [[menstrual cycle]]. [[Fertility awareness]] methods are used to discern when these changes occur by tracking changes in [[cervical mucus]] or [[basal body temperature]].

Male infertility is most commonly due to deficiencies in the [[semen]], and [[semen quality]] is used as a surrogate measure of male [[fecundity]].<ref name=who2010>{{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 = 6 | title = World Health Organization reference values for human semen characteristics | journal = Human Reproduction Update | volume = 16 | issue = 3 | pages = 231–245 | year = 2010 | pmid = 19934213 | doi = 10.1093/humupd/dmp048 | doi-access = free }}</ref> Male infertility may also be due to [[retrograde ejaculation]], [[low testosterone]], functional [[azoospermia]] (in which sperm is not produced or not produced in enough numbers) and obstructive azoospermia in which the pathway for the sperm (such as the [[vas deferens]]) is obstructed.<ref name="Carson 2021" /> 
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