Human chorionic gonadotropin (hCG) is a hormone for the maternal recognition of pregnancy produced by trophoblast cells that are surrounding a growing embryo (syncytiotrophoblast initially), which eventually forms the placenta after implantation.

[citation needed] Human chorionic gonadotropin is a glycoprotein composed of 237 amino acids with a molecular mass of 36.7 kDa, approximately 14.5kDa αhCG and 22.2kDa βhCG.

The two subunits create a small hydrophobic core surrounded by a high surface area-to-volume ratio: 2.8 times that of a sphere.

[7] beta-hCG is mostly similar to beta-LH, with the exception of a Carboxy Terminus Peptide (beta-CTP) containing four glycosylated serine residues that is responsible for hCG's longer half-life.

[citation needed] Like any other gonadotropins, it can be extracted from the urine of pregnant women or produced from cultures of genetically modified cells using recombinant DNA technology.

The lack of a visible fetus on vaginal ultrasound after βhCG levels reach 1500 mIU/mL is strongly indicative of an ectopic pregnancy.

[25] It must be taken into account, however, that total hCG levels may vary in a very wide range within the first 4 weeks of gestation, leading to false results during this period.

[24] Gestational trophoblastic disease like hydatidiform moles ("molar pregnancy") or choriocarcinoma may produce high levels of βhCG due to the presence of syncytiotrophoblasts, part of the villi that make up the placenta, and despite the absence of an embryo.

As ovulation will happen between 38 and 40 hours after a single HCG injection,[31] procedures can be scheduled to take advantage of this time sequence,[32][unreliable medical source?]

Female patients who have thrombosis, severe obesity, or thrombophilia should not be prescribed this medicine as they have a higher risk of arterial or venous thromboembolic events after or during a treatment with HCG Pubergen, Pregnyl.

[citation needed] In the case of male patients: A prolonged treatment with HCG Pubergen, Pregnyl is known to regularly lead to increased production of androgen.

Therefore: Patients who have overt or latent cardiac failure, hypertension, renal dysfunction, migraines, or epilepsy might not be allowed to start using this medicine or may require a lower dose of HCG Pubergen, Pregnyl.

This drug should be used with extreme caution in the treatment of prepubescent teenagers in order to reduce the risk of precocious sexual development or premature epiphyseal closure.

[citation needed] Both male and female patients who have the following medical conditions must not start a treatment with HCG Pubergen, Pregnyl: (1) Hypersensitivity to this drug or to any of its main ingredients.

[40] Mixed Martial Arts fighter Dennis Siver was fined $19,800 and suspended 9 months for being tested positive after his bout at UFC 168.

[42] Simeons, while studying pregnant women in India on a calorie-deficient diet, and obese boys with pituitary issues (Frölich's syndrome) treated with low-dose HCG, observed that both lost fat rather than lean (muscle) tissue.

[42] He reasoned that HCG must be programming the hypothalamus to do this in the former cases in order to protect the developing fetus by promoting mobilization and consumption of abnormal, excessive adipose deposits.

[42] Other researchers did not find the same results when attempting experiments to confirm Simeons' conclusions, and in 1976 in response to complaints the FDA required Simeons and others to include the following disclaimer on all advertisements:[43] These weight reduction treatments include the injection of HCG, a drug which has not been approved by the Food and Drug Administration as safe and effective in the treatment of obesity or weight control.

[48] On November 15, 2016, the American Medical Association (AMA) passed policy that "The use of human chorionic gonadotropin (HCG) for weight loss is inappropriate.

The meta-analysis found insufficient evidence supporting the claims that HCG is effective in altering fat-distribution, hunger reduction, or in inducing a feeling of well-being.

Moreover, it is highly unlikely that oral HCG is bioavailable due to the fact that digestive protease enzymes and hepatic metabolism renders peptide-based molecules (such as insulin and human growth hormone) biologically inert.

[citation needed] As of December 6, 2011[update], the United States Food and Drug Administration has prohibited the sale of homeopathic and over-the-counter hCG diet products and declared them fraudelent and banned.

[54][56][57] Catholic Bishops in Kenya[58] are among those who have spread a conspiracy theory[59] asserting that HCG forms part of a covert sterilization program, forcing denials from the Kenyan government.

[58] In order to induce a stronger immune response, some versions of human chorionic gonadotropin-based anti-fertility vaccines were designed as conjugates of the β subunit of HCG covalently linked to tetanus toxoid.

[33][60] It was alleged that a non-conjugated tetanus vaccine used in developing countries was laced with a human chorionic gonadotropin-based anti-fertility drug and was distributed as a means of mass sterilization.

[63] Finally, independent testing of the tetanus vaccine by Kenya's health authorities revealed no traces of the human chorionic gonadotropin hormone.