- HCG is a hormone almost exclusively produced during pregnancy, and plays an important role in sustaining an embryo until the placenta is formed.
- At-home pregnancy tests work by detecting hCG in the urine.
- HCG is produced in very minimal quantities in non-pregnant women and men and does not appear to play an appreciable role in body functions.
- Higher-than-normal levels of hCG may also be present in certain types of cancers in males and non-pregnant females.
- This article was reviewed by Felice Gersh, MD, an OB-GYN and founder and director of the Integrative Medical Group of Irvine.
- Visit Insider’s homepage for more stories .
Known as the “pregnancy hormone,” human chorionic gonadotropin (hCG) is a type of hormone that is produced in large amounts during pregnancy, with levels peaking during the first 8 to 11 weeks of pregnancy, and can be detected in the urine of pregnant women with at-home pregnancy tests.
However, pregnant women aren’t the only ones who produce it. Certain cancers and other medical conditions can lead non-pregnant women and men to produce moderate to high levels of hCG.
Here’s what you need to know about hCG, whether you’re pregnant or not.
The role of hCG in pregnancy
“HCG in its regular form is produced almost exclusively by a pregnant woman by special cells which become a part of the placenta, called the syncytiotrophoblast … which is why we see it in such high levels in pregnancy,” says Dr. Kristina Mixer, MD with Spectrum Health.
She explains that during pregnancy, hCG’s primary role is to support the production of the hormone progesterone by the ovaries until the placenta is sufficiently formed and can produce adequate amounts of progesterone on its own, typically by 10 weeks gestation.
That’s important because progesterone is absolutely vital for healthy reproduction. It’s responsible for facilitating the successful attachment of the embryo within the uterine cavity, modulating the immune system to prevent miscarriages, and for suppressing uterine contractions. In certain situations of recurrent pregnancy loss, healthcare providers will sometimes prescribe progesterone or hCG as a way to support the pregnancy early on.
Once you’ve conceived, the body begins to produce hCG as soon as a fertilised egg implants into the uterine wall, and it typically takes another 8 to 14 days before the hCG levels rise enough to be detected by an at-home pregnancy test. Most urine pregnancy tests will detect a pregnancy at the time of your first missed period.
The role of hCG in molar pregnancy
A woman can exhibit elevated hCG levels after a molar pregnancy, as well. Molar pregnancy happens after an egg is fertilised, but the tissue that usually grows into the placenta forms an abnormal growth, instead. So the egg never develops into an embryo.
Women often have the molar tissue removed, but sometimes it can return and develop into a uterine tumour. This can lead to certain types of cancer like choriocarcinoma and malignant gestational trophoblastic disease. Since these tumours involve the same cells that produce hCG, women with these conditions often have elevated hCG levels, as well, even though they’re not pregnant.
HCG in men and women who are not pregnant
“In non-pregnant women or men, levels are usually very low and do not play an important role in daily hormone function,” Mixer says. However, there are some situations that could lead to moderate to high hCG levels in a non-pregnant woman or man, such as:
- Response to chemotherapy.
- Familial hCG, a very rare genetic condition.
- Gestational trophoblastic disease, which is associated with very high levels of hCG.
“All of these conditions should be discussed with and managed by a physician or healthcare provider,” says Mixer.
In addition to medical conditions that could lead to elevated hCG levels, some cases of high hCG are the result of hCG injections. “We often see this in male athletes in an effort to boost testosterone production,” Mixer says. This occurs because hCG is very similar to the pituitary hormone LH, which stimulates the production of testosterone in the testes.
HCG can also be used as an identifying marker during pregnancy to detect Down’s Syndrome. “A certain subtype of hCG can be measured to predict the likelihood of Down Syndrome affecting the foetus,” Mixer says.
Certain types of cancers can produce higher-than-normal levels of hCG in both men and women. The types of cancers that can lead to elevated hCG levels include:
Measuring hCG levels in the above types of cancers can help identify tumours in the body, diagnose cancer, or evaluate how well a cancer treatment is working.
Related stories about pregnancy:
- How to choose a pregnancy test at the store and why digital tests aren’t necessarily better
- Home pregnancy tests are very accurate if you use them correctly
- When to take a pregnancy test for the most accurate result
- How much weight you should gain during pregnancy, according to doctors
- Foods to avoid during pregnancy and how to still stay healthy
- How long it takes to recover from a C-section before you can drive a car, take a bath, and have sex
- Yes, Tylenol is safe for pregnancy. Here’s the right dosage