Editing Human chorionic gonadotropin (section)

== Function ==

Human chorionic gonadotropin interacts with the [[LHCG receptor]] of the ovary and promotes the maintenance of the [[corpus luteum]] for the [[maternal recognition of pregnancy]] at the beginning of [[pregnancy]]. This allows the corpus luteum to [[Secretion|secrete]] the hormone [[progesterone]] during the first trimester. Progesterone enriches the [[uterus]] with a thick [[Endometrium|lining]] of [[blood vessel]]s and [[capillary|capillaries]] so that it can sustain the growing [[fetus]].<ref>{{Cite web|title=Stages of Fetal Development - First Trimester {{!}} Department of Health {{!}} State of Louisiana|url=https://ldh.la.gov/index.cfm/page/986|access-date=2021-02-16|website=ldh.la.gov}}</ref>

It has been hypothesized that hCG may be a placental link for the development of local maternal [[Immune tolerance|immunotolerance]].<ref>{{cite journal | vauthors = Schumacher A, Heinze K, Witte J, Poloski E, Linzke N, Woidacki K, Zenclussen AC | title = Human chorionic gonadotropin as a central regulator of pregnancy immune tolerance | journal = Journal of Immunology | volume = 190 | issue = 6 | pages = 2650–2658 | date = March 2013 | pmid = 23396945 | doi = 10.4049/jimmunol.1202698 | doi-access = free }}</ref> For example, hCG-treated endometrial cells induce an increase in T cell [[apoptosis]] (dissolution of [[T cell]]s).  These results suggest that hCG may be a link in the development of peritrophoblastic immune tolerance, and may facilitate the [[trophoblast]] invasion, which is known to expedite fetal development in the endometrium.<ref>{{cite journal | vauthors = Kayisli UA, Selam B, Guzeloglu-Kayisli O, Demir R, Arici A | title = Human chorionic gonadotropin contributes to maternal immunotolerance and endometrial apoptosis by regulating Fas-Fas ligand system | journal = Journal of Immunology | volume = 171 | issue = 5 | pages = 2305–2313 | date = September 2003 | pmid = 12928375 | doi = 10.4049/jimmunol.171.5.2305 | doi-access = free }}</ref> It has also been suggested that hCG levels are linked to the severity of [[morning sickness]] or [[hyperemesis gravidarum]] in pregnant women.<ref name="pmid10636378">{{cite journal | vauthors = Askling J, Erlandsson G, Kaijser M, Akre O, Ekbom A | title = Sickness in pregnancy and sex of child | journal = Lancet | volume = 354 | issue = 9195 | pages = 2053 | date = December 1999 | pmid = 10636378 | doi = 10.1016/S0140-6736(99)04239-7 | s2cid = 43817834 }}</ref>

Because of its similarity to LH, hCG can also be used clinically to induce ovulation in the ovaries as well as testosterone production in the testes. As the most abundant biological source is in women who are presently pregnant, some organizations collect urine from pregnant women to extract hCG for use in fertility treatment.{{cn|date=September 2023}}

Human chorionic gonadotropin also plays a role in cellular differentiation/proliferation and may activate apoptosis.{{cn|date=September 2023}}