What Is hCG, the Pregnancy Hormone?

By:    Medically Reviewed: Tom Iarocci, MD   Published: August 13, 2014

Human chorionic gonadotropin (hCG) is a hormone made by the body during pregnancy.

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Human chorionic gonadotropin, or hCG, is a hormone that is produced by the body in copious amount during pregnancy. Typically, levels of the hormone are measured by a blood or urine test during the early weeks of pregnancy.

“As soon as pregnancy occurs, the placenta and other gestational tissues start producing hCG,” says gynecologist Nanette Santoro, MD, professor of obstetrics and gynecology at the University of Colorado School of Medicine. Typically, this helpful pregnancy hormone can be detected with a blood test as soon as 11 days after conception, and detected in the urine after about 12 to 14 days.

What is hCG’s Role in Pregnancy?

Within days of missing your period, a blood test will be able to tell you if you are pregnant by measuring the levels of hCG in your blood. In a normally developing pregnancy, the levels will typically double within 48 hours.

“The hCG hormone is a long-acting version of luteinizing hormone (which ensures that ovulation occurs and makes the corpus luteum form during the normal menstrual cycle),” explains Santoro. “Its primary function is maintaining progesterone production.”  Producing enough progesterone is essential for supporting a healthy pregnancy — without enough of it, a miscarriage may occur.

Maternal blood has detectable levels of hCG about 3 days after implantation of the human embryo. The outer layer of the embryo’s cells gives rise to the fetal part of the placenta, which is believed to be the main site of hCG production, but this is an active area of research. While it’s important not to read too much into hCG levels, the numbers do have some meaning: “The amount of hCG is roughly proportional to the amount of pregnancy tissue,” says Santoro.  Each baby usually has its own placenta in the case of fraternal (dizygotic) twins. “So when there are twins or triplets growing, the hCG levels are higher.”

Abnormally high levels of hCG can also be an indicator of trouble, such as placental cancer and some kinds of abnormal pregnancies.  In a normal pregnancy, the levels rise exponentially for the first six to eight weeks. HCG pregnancy hormones peak by 11 weeks, then decline and level off for the remainder of your pregnancy.

The hCG Diet: Can It Help Me Lose Weight?

No.  If you’ve ever been pregnant (and probably worried about gaining weight) this may seem incredible or counterintuitive, but a bizarre modern diet craze has people taking supplements or injections of the pregnancy hormone hCG in order to attempt lose weight.

(This unsubstantiated diet plan was actually first developed in the 1950’s, enjoyed wide popularity in the 70’s and has recently made a resurgence. Ignore it.)

The plan involves not only taking daily injections or oral supplements of hCG, but also following an extremely restrictive, 500-calorie-a-day diet for eight weeks. Chances are good that anyone following this diet as directed will lose weight, but experts contend that any pounds dropped will be a result of the very low caloric intake — not the addition of hCG.

The diet is dangerous because it’s very difficult to get enough protein and other essential nutrients while eating such a small quantity of food. No hCG supplements are approved by the FDA for weight loss.

Injections of hCG can be legally provided by a doctor, but not for weight loss, since they are FDA approved to treat fertility issues. But over-the-counter hCG supplements are not approved by the FDA — in fact, the agency has sent warning letters to several companies that market these dangerous so-called diet tools.

There are several health concerns related to taking any hormone improperly – and for the wrong reasons. “Giving hCG to a non-pregnant woman will lead to an increase in androgen production, and that can cause acne, facial and/or body hair growth and, in susceptible women, could even cause head hair loss,” cautions Santoro. “Taking hCG when you’re not pregnant can also lead to abnormalities in blood cholesterol levels and more 'bad' cholesterol and less 'good' cholesterol.”

Next Steps

For Patients

If you’re looking to lose weight, start by consulting your doctor for help finding the best plan. Beware of any programs that promise fast, effortless results. If they sound too good to be true, they most likely are. 

For Family Caregivers

When someone you care about seems desperate to loose weight, encourage healthy methods that have stood the test of time. You might point out that too few calories in a day undermines your loved one’s efforts to lose weight and reduces the likelihood of success.

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