HCG (Human Chorionic Gonadotropin) is often called the pregnancy hormone because it is made by cells formed in the placenta, which nourishes the egg after it has been fertilized and becomes attached to the uterine wall. Levels can first be detected by a blood test about 11 days after conception and about 12-14 days after conception by a urine test.
Typically, the hCG levels will double every 72 hours. The level will reach its peak in the first 8-11 weeks of pregnancy and then will decline and level off for the remainder of the pregnancy.
What You Need to Know About hCG Levels:
- As you get further along in pregnancy and the hCG level gets higher, the time it takes to double can increase to about every 96 hours.
- Caution must be used in making too much of hCG numbers. A normal pregnancy may have low hCG levels and result in a perfectly healthy baby. The results from an ultrasound after 5 -6 weeks gestation are much more accurate than using hCG numbers.
- An hCG level of less than 5 mIU/mL is considered negative for pregnancy, and anything above 25 mIU/mL is considered positive for pregnancy.
- An hCG level between 6 and 24 mIU/mL is considered a grey area, and you’ll likely need to be retested to see if your levels rise to confirm a pregnancy.
- The hCG hormone is measured in milli-international units per milliliter (mIU/mL).
- A transvaginal ultrasound should be able to show at least a gestational sac once the hCG levels have reached between 1,000 – 2,000 mIU/mL. Because levels can differentiate so much and conception dating can be wrong, a diagnosis should not be made by ultrasound findings until the hCG level has reached at least 2,000 mIU/mL.
- A single reading is not enough information for most diagnoses. When there is a question regarding the health of the pregnancy, multiple testings of hCG done a couple of days apart give a more accurate assessment of the situation.
- The hCG levels should not be used to date a pregnancy since these numbers can vary so widely.
- There are two common types of hCG tests. A qualitative test detects if hCG is present in the blood. A quantitative test (or beta) measures the amount of hCG actually present in the blood.
Guideline to hCG levels in weeks during pregnancy
- 3 weeks LMP: 5 – 50 mIU/mL
- 4 weeks LMP: 5 – 426 mIU/mL
- 5 weeks LMP: 18 – 7,340 mIU/mL
- 6 weeks LMP: 1,080 – 56,500 mIU/mL
- 7 – 8 weeks LMP: 7, 650 – 229,000 mIU/mL
- 9 – 12 weeks LMP: 25,700 – 288,000 mIU/mL
- 13 – 16 weeks LMP: 13,300 – 254,000 mIU/mL
- 17 – 24 weeks LMP: 4,060 – 165,400 mIU/mL
- 25 – 40 weeks LMP: 3,640 – 117,000 mIU/mL
- Non-pregnant females: 0 – 5 mIU/mL
- Postmenopausal females: 0 – 8 mIU/mL
* These numbers are just a guideline – every woman’s level of hCG can rise differently. It is not necessarily the level that matters, but rather the change in the level.
What Does a Low hCG Level Mean?
A low hCG level can mean any number of things and should be rechecked within 48-72 hours to see how the level is changing. A low level can indicate:
Is a High hCG Level a Bad Thing?
A high level of hCG can also mean a number of things and should be rechecked within 48-72 hours to evaluate changes in the level. A high level can indicate:
Should I Check My hCG level Regularly?
It’s not common for doctors to routinely check your hCG levels unless you are showing signs of a potential problem.
A health care provider may recheck your levels if you are bleeding, experiencing severe cramping, or have a history of miscarriage.
What Can I Expect After a Pregnancy Loss?
Most women can expect their levels to return to a non-pregnant range about 4 – 6 weeks after a pregnancy loss has occurred.
This can differentiate by how the loss occurred (spontaneous miscarriage, D & C procedure, abortion, natural delivery) and how high the levels were at the time of the loss.
Healthcare providers usually will continue to test hCG levels after a pregnancy loss to ensure they return back to <5.0.
What Can Interfere With My hCG Levels?
If you get a positive test result, you are most likely pregnant. False positives are extremely rare. However, there are some conditions that may cause a false positive, such as certain types of cancer and early miscarriage. Some antibodies may also interfere with test results.
Medications that contain hCG may interfere with hCG levels, as well.
These medications are often used infertility treatments, and your health care provider should advise you on how they may affect a test.
All other medications such as antibiotics, pain relievers, contraception or other hormone medications should not have any effect on a test that measures hCG.
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Compiled using information from the following sources:
1. U.S. Food and Drug Administration
2. Bashir, I; Ihenetu, K; Miller, J.J.; Gim, M.; Lippmann, S. A Positive Pregnancy Test in the Post-Menopausal Psychiatric Patient — What to Think? Psychiatry (Edgemont). Feb. 2006.