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[ 0 => '{{Sex (biology) sidebar}}', 1 => ''''Human reproduction''' is any form of [[sexual reproduction]] resulting in [[human fertilization]]. It typically<!-- NOTE: "Typically" is here because, as is clear from the rest of the lead and lower in the article, human reproduction can also be achieved via artificial insemination and assisted reproductive technology.--> involves [[sexual intercourse]] between a man and a woman. During sexual intercourse, the interaction between the [[human male reproductive system|male]] and [[human female reproductive system|female reproductive systems]] results in [[fertilization]] of the woman's [[ovum]] by the man's [[sperm]]. These are specialized reproductive [[cell (biology)|cells]] called [[gamete]]s, created in a process called [[meiosis]]. While normal cells contains 46 [[chromosome]]s, 23 pairs, gamete cells only contain 23 chromosomes, and it is when these two cells merge into one [[zygote]] cell that [[genetic recombination]] occurs and the new zygote contains 23 chromosomes from each parent, giving them 23 pairs. A typical 9-month [[gestation period]] is followed by [[childbirth]]. The fertilization of the ovum may be achieved by [[artificial insemination]] methods, which do not involve sexual intercourse. [[Assisted reproductive technology]] also exists.', 2 => '', 3 => '== Anatomy ==', 4 => '[[File:Human reproductive system charts used by Lao students.jpg|thumb|Lao students study a display about the human reproductive system. Exhibits such as this are rare in many less-developed countries, such as [[Laos]]. This event was held by [[Big Brother Mouse]], a literacy and education project, which added Lao explanations to a commercially available set of panels that were printed with English.]]', 5 => '{{Further information|Human reproductive system}}', 6 => '', 7 => '===Human male ===', 8 => '{{details|Human male reproductive system}}', 9 => 'The male reproductive system contains two main divisions: the [[testicle|testes]] where [[sperm]] are produced, and the [[human penis|penis]]. In humans, both of these organs are outside the [[abdominal cavity]]. Having the testes outside the abdomen facilitates temperature regulation of the sperm, which require specific temperatures to survive about 2-3&nbsp;°C less than the normal body temperature i.e. 37&nbsp;°C. In particular, the extraperitoneal location of the testes may result in a 2-fold reduction in the heat-induced contribution to the spontaneous mutation rate in male germinal tissues compared to tissues at 37&nbsp;°C.<ref>{{cite journal | author = Baltz RH, Bingham PM, Drake JW | year = 1976 | title = Heat mutagenesis in bacteriophage T4: The transition pathway | journal = Proc. Natl. Acad. Sci. USA | volume = 73 | issue = 4| pages = 1269–1273 | pmid = 4797 | pmc = 430244 | doi = 10.1073/pnas.73.4.1269 }}</ref> If the testicles remain too close to the body, it is likely that the increase in temperature will harm the spermatozoa formation, making conception more difficult. This is why the testes are carried in an external pouch viz. [[scrotum]] rather than within the abdomen; they normally remain slightly cooler than body temperature, facilitating sperm production.', 10 => '', 11 => '=== Human female ===', 12 => '{{details|Female reproductive system}}', 13 => 'The female reproductive system likewise contains two main divisions: the [[vagina]] and the [[Ovum]].', 14 => '', 15 => 'The ovum meets with [[sperm cell]], a sperm may penetrate and merge with the egg, fertilizing it with the help of certain hydrolytic enzymes present in the acrosome. The fertilization usually occurs in the [[oviduct]]s, but can happen in the uterus itself. The [[zygote]] then becomes [[Implantation (human embryo)|implanted]] in the lining of the uterus, where it begins the processes of [[embryogenesis]] and [[morphogenesis]]. When the [[fetus]] is developed enough to survive outside of the [[uterus]], the cervix dilates and contractions of the uterus propel it through the birth canal, which is the vagina.', 16 => '', 17 => 'The ova, which are the female sex cells, are much larger than the spermatozoon and are normally formed within the ovaries of the female fetus before its birth. They are mostly fixed in location within the ovary until their transit to the uterus, and contain nutrients for the later [[zygote]] and [[embryo]]. Over a, usually, regular interval known as the [[menstrual cycle]], in response to hormonal signals, a process of [[oogenesis]] matures one ovum which is released and sent down the Fallopian tube. If not fertilized, this egg is flushed out of the system through [[menstrual cycle|menstruation]].', 18 => '', 19 => '== Process of fertilization ==', 20 => '[[File:Biological Life Cycle of Humans.svg|thumb|This model of the biological life cycle of a human shows the basic processes involved and the order that they are in.]]', 21 => '[[Image:Da Vinci Coition of a Hemisected Man and Woman Luc Viatour.jpg|thumb|200px|right|"Coition of a Hemisected Man and Woman" (c. 1492) by [[Leonardo da Vinci]].]]', 22 => 'Human reproduction normally begins with copulation, followed by nine months of pregnancy before childbirth, though it may be achieved through [[artificial insemination]]. Many years of parental care are required before a human child becomes independent, typically between twelve and eighteen or more. Pregnancy can be avoided with the use of contraceptives such as [[condom]]s and [[Intrauterine device]]s.', 23 => '', 24 => '=== Copulation ===', 25 => '{{Main article|Sexual intercourse}}', 26 => 'Human reproduction naturally takes place as [[internal fertilization]] by sexual intercourse. During this process, the male inserts his penis, which needs to be [[erection|erect]], into the female's [[vagina]], and then either partner initiates rhythmic [[pelvic thrust]]s until the male [[ejaculate]]s semen, which contains sperm, into the vaginal canal. This process is also known as "coitus", "mating", "having sex", or, [[euphemistically]], "making love". The sperm and the ovum are known as [[gametes]] (each containing half the genetic information of the parent, created through [[meiosis]]). The sperm (being one of approximately 250 million sperm in a typical male ejaculation) travels through the vagina and cervix into the uterus or Fallopian tubes. Only 1 in 14 million of the ejaculated sperm will reach the Fallopian tube. The egg simultaneously moves through the Fallopian tube away from the ovary. One of the sperm encounters, penetrates and fertilizes the ovum, creating a [[zygote]]. Upon [[human fertilization|fertilization]] and [[Implantation (human embryo)|implantation]], gestation of the fetus then occurs within the female's uterus.<ref>{{cite journal |author=Ghazal, S, Kulp Makarov, J |url=http://www.glowm.com/section_view/heading/Egg%20Transport%20and%20Fertilization/item/316 |title=Egg Transport and Fertilization |journal= Glob. libr. women's med. |year=2014 |issn= 1756-2228 |doi=10.3843/GLOWM.10317 |accessdate=May 8, 2016 |display-authors=etal}}</ref><ref>{{cite web |url=https://www.ucsfhealth.org/education/conception_how_it_works/ |title=Conception: How It Works |publisher=The Regents of The University of California |year=2002 |accessdate=May 8, 2016 }}</ref><ref>{{cite web |url=http://www.completefertility.co.uk/fertility_basics.php |title=Fertility Basics |work=Complete Fertility Centre Southampton |publisher= Complete Fertility Ltd |year=2015 |accessdate=May 8, 2016 }}</ref><ref>{{cite web |url=http://www.webmd.com/baby/guide/understanding-conception |title=Conception & Pregnancy: Ovulation, Fertilization, and More |publisher=WebMD, LLC |year=2016 |accessdate=May 8, 2016 }}</ref> ', 27 => '', 28 => '[[File:Pregnancy chance by day near ovulation.jpg|thumb|Chance of [[human fertilization|fertilization]] by [[menstrual cycle]] day relative to ovulation.<ref name="DunsonBaird1999">{{cite journal|last1=Dunson|first1=D.B.|last2=Baird|first2=D.D.|last3=Wilcox|first3=A.J.|last4=Weinberg|first4=C.R.|title=Day-specific probabilities of clinical pregnancy based on two studies with imperfect measures of ovulation|journal=Human Reproduction|volume=14|issue=7|year=1999|pages=1835–1839|issn=1460-2350|doi=10.1093/humrep/14.7.1835|doi-access=free|pmid=10402400}}</ref>]]', 29 => '[[Pregnancy_rate#Pregnancy_rate_for_sexual_intercourse|Pregnancy rates for sexual intercourse]] are highest during the [[menstrual cycle]] time from some 5 days before until 1 to 2 days after ovulation.<ref>Pages.242,374 in: {{cite book|title=Taking Charge of Your Fertility|url=https://archive.org/details/takingchargeofyo00toni|url-access=registration|last=Weschler|first=Toni|publisher=HarperCollins|year=2002|isbn=0-06-093764-5|edition=Revised|location=New York|pages=[https://archive.org/details/takingchargeofyo00toni/page/359 359–361]}}</ref> For optimal pregnancy chance, there are recommendations of sexual intercourse every 1 or 2 days,<ref>{{cite web|url=https://www.mayoclinic.org/healthy-lifestyle/getting-pregnant/in-depth/how-to-get-pregnant/art-20047611|title=How to get pregnant|website=[[Mayo Clinic]]|date=2016-11-02|accessdate=2018-02-16}}</ref> or every 2 or 3 days.<ref>{{cite web|url=https://www.nice.org.uk/guidance/cg156/ifp/chapter/trying-for-a-baby|title=Fertility problems: assessment and treatment, Clinical guideline [CG156]|website=[[National Institute for Health and Care Excellence]]|accessdate=2018-02-16}} Published date: February 2013. Last updated: September 2017</ref> Studies have shown no significant difference between different [[sex positions]] and pregnancy rate, as long as it results in [[ejaculation]] into the [[vagina]].<ref name=americanpregnancy>{{cite web|url=http://americanpregnancy.org/getting-pregnant-ebook/p7M7O0q1c71703C/gettingpregnant.pdf|title=The Essential Guide to Getting Pregnant|website=American Pregnancy Association|author=Dr. Philip B. Imler & David Wilbanks|access-date=2018-02-16|archive-url=https://web.archive.org/web/20180601033115/http://americanpregnancy.org/getting-pregnant-ebook/p7M7O0q1c71703C/gettingpregnant.pdf|archive-date=2018-06-01|url-status=dead}}</ref>', 30 => '===Alternative methods===', 31 => '', 32 => 'As an alternative to natural sexual intercourse, there exists [[artificial insemination]], where sperm is introduced into the female reproductive system. There are also many methods of [[assisted reproductive technology]], such as [[in vitro fertilization]], where one or more [[oocyte|egg cells]] are retrieved from a woman's ovaries and co-incubated with sperm outside the body. The resulting embryo can then be reinserted into the woman's womb.', 33 => '', 34 => '===Pregnancy===', 35 => '{{main article|Pregnancy}}', 36 => 'Pregnancy is the period of time during which the fetus develops, dividing via [[mitosis]] inside the female. During this time, the fetus receives all of its [[nutrition]] and oxygenated blood from the female, filtered through the [[placenta]], which is attached to the fetus' [[abdomen]] via an [[umbilical cord]]. This drain of [[nutrient]]s can be quite taxing on the female, who is required to ingest slightly higher levels of [[calorie]]s. In addition, certain [[vitamin]]s and other nutrients are required in greater quantities than normal, often creating abnormal eating habits. Gestation period is about 266 days in humans. While in the uterus, the baby first endures a very brief zygote stage, then the embryonic stage, which is marked by the development of major organs and lasts for approximately eight weeks, then the fetal stage, which revolves around the development of bone cells while the fetus continues to grow in size.<ref>{{cite book|last1=Feist|first1=Gregory J.|last2=Rosenberg|first2=Erika L.|title=Psychology: Perspectives and Connections|publisher=McGraw Hill|isbn=978-0-07-803520-3|pages=(171–172)|edition=Second|url-access=registration|url=https://archive.org/details/isbn_9780078035203}}</ref>', 37 => '', 38 => '===Birth===', 39 => '[[Image:Postpartum baby2.jpg|250px|thumb|Newborn infant and mother]]', 40 => '{{main article|Childbirth}}', 41 => 'Once the fetus is sufficiently developed, chemical signals begin the process of birth, which begins with the fetus being pushed out of the birthing canal. The newborn, which is called an [[infant]] in humans, should typically begin [[Respiration (physiology)|respiration]] on its own shortly after birth. Not long after, the placenta eventually falls off on its own. The person assisting the birth may also sever the umbilical cord.', 42 => '', 43 => '===Parental care===', 44 => '{{Main article|Parenting}}', 45 => 'A human baby is nearly helpless and the growing child requires high levels of parental care for many years. One important type of early parental care is [[lactation]], feeding the baby milk from the mother's [[mammary gland]]s in her [[breast]]s.<ref>[http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Sexual_Reproduction.html Sexual Reproduction in Humans.] 2006. John W. Kimball. Kimball's Biology Pages, and online textbook.</ref>', 46 => '', 47 => '==See also==', 48 => '*[[Heterosexuality]]', 49 => '*[[Antinatalism]]', 50 => '*[[Evolution of sexual reproduction]]', 51 => '*[[Female infertility]]', 52 => '*''[[Human Reproduction (journal)]]', 53 => '*''[[Journal of Human Reproductive Sciences]]''', 54 => '*[[Male infertility]]', 55 => '*[[Natalism]]', 56 => '*[[Paternal age effect]]', 57 => '*[[Reproduction]]', 58 => '*[[Reproductive system]]', 59 => '', 60 => '==References==', 61 => '{{reflist}}', 62 => '', 63 => '==Further reading==', 64 => '* Hopwood, Nick, Rebecca Flemming, Lauren Kassell, eds. ''Reproduction: Antiquity to the Present Day'' (Cambridge UP, 2018). Illustrations. xxxv + 730 pp. {{ISBN|978-1-107-06802-5}} [https://www.amazon.com/Reproduction-Antiquity-Present-Nick-Hopwood/dp/1107068029/ excerpt] also [http://www.h-net.org/reviews/showpdf.php?id=53889 online review] 44 scholarly essays by historians.', 65 => '{{Pregnancy}}', 66 => '{{Reproductive physiology}}', 67 => '', 68 => '[[Category:Human reproduction| ]]' ]