Human chorionic gonadotropin (hCG)
A rare case of a hormone whose biology has been described for nearly a century and whose regulatory status is firmly established: hCG holds a place apart among the molecules documented here.
- Research Use Only
- Molecule under study
- Living document
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- Current research state
- Long-approved medicine for fertility and hypogonadotropic hypogonadism — extensively described in pharmacopoeias.
- Current clinical phase
- Established clinical use (outside PHL, which presents it as Research Use Only)
- Last update
- 21 July 2026 · Reference fact sheet v1.0
- Living document
- Updated regularly as research progresses.
What is Human chorionic gonadotropin (hCG)?
Human chorionic gonadotropin (hCG) is a glycoprotein hormone of the gonadotropin family, alongside LH and FSH; it also shares its α subunit with TSH, a thyroid-stimulating hormone that is not a gonadotropin.
It is physiologically produced by placental syncytiotrophoblast cells from the earliest days of pregnancy — it is the hormone detected by pregnancy tests.
Therapeutically, it is used as an LH substitute: either to trigger ovulation (female fertility) or to stimulate endogenous testosterone production in men with hypogonadotropic hypogonadism.
Names you may come across
This molecule may appear under several names in the scientific, clinical or technical literature. Here are the main designations you may come across.
Standard abbreviation, most commonly used clinically.
Official French name.
INN of the recombinant form (Ovitrelle®).
Understanding it simply
Three simple reference points for understanding hCG.
The pregnancy hormone
hCG is naturally produced by the placenta from the earliest days of pregnancy — it is what urine and blood pregnancy tests detect.
An LH mimic
It resembles LH so closely that it activates the same receptor, with a longer-lasting action. This makes it useful in fertility and male endocrinology.
A hormone, not a diet
Highly restrictive diets combined with hCG injections have no scientific basis and are explicitly discouraged by health authorities.
What research shows today
Science advances step by step. We clearly distinguish what is firmly established from what remains under study.
- Heterodimeric glycoprotein composed of an α subunit (shared with LH, FSH, and TSH) and a specific β subunit. — established
- High-affinity binding to the LHCGR receptor (the shared LH/hCG receptor). — established
- LH-analogue biological effects: stimulation of Leydig cells (testosterone) and ovulation triggering. — established
- Available forms: urinary (extracted from the urine of pregnant women) and recombinant (choriogonadotropin alfa). — established
- Its optimal role in combination with FSH in certain protocols remains a subject of clinical discussion. — ongoing
Extensive clinical literature, with established medical use since the 1930s in fertility and male hypogonadotropic hypogonadism. Approved urinary and recombinant forms (Pregnyl, Ovitrelle).
What the research shows
- Fully characterized structure, placental biosynthesis, and pharmacokinetics.
- Efficacy as an ovulation trigger in ovarian stimulation protocols (IVF, IUI) demonstrated in numerous controlled studies.
- Efficacy as a stimulator of testicular steroidogenesis in hypogonadotropic hypogonadism demonstrated in clinical practice.
- Historical use in pediatrics for cryptorchidism, with its value now debated in favor of surgery.
What still remains to be studied
- Optimal use of hCG + FSH regimens versus recombinant LH in fertility protocols.
- Role in maintaining fertility in men receiving exogenous testosterone — a subject of scientific debate.
- Ultra-purified forms and individualized dosing: ongoing optimization.
What we know today
Not all information carries the same weight of evidence. We therefore present it across three clearly distinct levels, from the most solid to the most indicative.
What scientific publications show
Scientific evidence- hCG and its receptor LHCGR have been extremely well characterized for more than 50 years.
- Clinical evidence of efficacy as an ovulation trigger and testicular stimulant is strong and incorporated into professional society recommendations.
- French and European reproductive medicine guidelines govern its use.
What some professionals report
Documented- Endocrinologists and reproductive medicine physicians have used hCG for decades with standardized protocols.
- The main risks to monitor are ovarian hyperstimulation syndrome (in women) and polycythemia / gynecomastia (in men).
What the community reports
Field observations- Informal community reports often concern off-label uses (recovery of the HPT axis after androgen cycles) — these uses are not clinically validated outside the medical setting.
- Individual observations do not replace medical recommendations.
hCG is a hormone with well-established medical uses, but its uses outside the medical setting are not supported by the same level of evidence.
How does Human chorionic gonadotropin (hCG) work?
hCG shares the LH receptor and reproduces its effects, with a longer duration of action.
- LHCGR receptor
- A shared LH/hCG receptor, present on Leydig cells (testis) and on theca and corpus luteum cells (ovary).
- Leydig cells
- In men: stimulation of steroidogenesis and production of intratesticular and serum testosterone.
- Ovarian follicle
- In women: triggering the resumption of oocyte meiosis and ovulation when the follicle is mature.
- Corpus luteum
- Support for progesterone secretion in early pregnancy.
The long plasma half-life of hCG (approximately 24-36 h for the urinary-derived form) is what functionally distinguishes it from endogenous LH (half-life ~ 20 min).
Clinical trials timeline
A molecule under study progresses step by step. Here, simply, is where the research currently stands.
- Discovery· 1927Completed
Ascheim-Zondek test
First indirect detection of hCG in the urine of pregnant women.
- Development· 1930s-1960sCompleted
Extraction and therapeutic use
Development of urinary-derived hCG preparations and initial uses in fertility treatment.
- Research· 1970s-1980sCompleted
Molecular characterization
Sequencing of the α and β subunits and characterization of the LHCGR receptor.
- Development· 2000sCompleted
Recombinant hCG
Market introduction of genetically engineered choriogonadotropin alfa (Ovitrelle®).
- Ongoing· CurrentlyOngoing
Protocol optimization
Ongoing research into ovarian stimulation regimens and male hypogonadotropic hypogonadism.
Available analyses
No analytical document has been published for this molecule to date.
Open the analysis libraryFrequently asked questions
Is hCG an approved medicine?
Established: yes, in many countries, in urinary-derived (Pregnyl®) or recombinant (Ovitrelle®) form. PHL presents it for educational purposes (Research Use Only) — no therapeutic use is proposed.
Why is it called the “pregnancy hormone”?
Established: it is produced by the placenta from the first days of pregnancy. It is the hormone detected by pregnancy tests.
What is the difference between hCG and LH?
Established: they share the same LHCGR receptor. hCG has a much longer half-life than LH, which explains its therapeutic value.
Does hCG cause weight loss?
Established: no. Very-low-calorie diets combined with hCG injections have no scientific basis and have been explicitly discouraged by the FDA since 2011.
Can it stimulate testosterone production?
Established: yes — this is indeed its main medical use in men with hypogonadotropic hypogonadism, under specialist medical supervision.
What adverse effects are possible?
Established: in women, a risk of ovarian hyperstimulation syndrome. In men, gynecomastia, polycythemia or mood disturbances may occur with prolonged high doses.
Scientific publications
A selection of reference publications and institutional sources. An evolving bibliography.
Testosterone: Action, Deficiency, Substitution
Nieschlag E., Behre H. M. (eds.) · Cambridge University Press (référence de pharmacopée) · 2012
Glossary
- hCG
- Human chorionic gonadotropin, a glycoprotein hormone produced by the placenta.
- LHCGR
- A shared receptor for LH and hCG, expressed on Leydig cells and ovarian theca cells.
- Hypogonadotropic hypogonadism
- Impaired gonadal function due to a central defect (hypothalamus / pituitary).
- Leydig cells
- Testicular cells that produce testosterone in response to LH or hCG.
- Ovulation
- Release of the oocyte from the mature ovarian follicle.
- Ovarian hyperstimulation syndrome
- A possible complication of fertility treatments, involving an excessive ovarian response.
Continue your discovery
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Reference fact sheet — version 1.0, updated on 21 July 2026. The full regulatory and scientific framework is gathered in the “Important information” box at the top of the fact sheet.