Last Updated on May 27, 2021 by Ines
The hCG (human chorionic gonadotropin hormone) is a hormone that is produced only in pregnancy. It is a hormone whose presence in the urine is detected by pregnancy tests. The pregnancy hormone hCG is also the one to blame for your nausea and vomiting in early pregnancy. But, let’s look into what is a pregnancy hormone hCG a little more in detail.
Although there are many pregnancy hormones, the hCG is the only one, which is made only during pregnancy. Therefore, if someone talks about pregnancy hormone, that probably refers to a human chorionic gonadotropin hormone (hCG).
What is the role of hCG in early pregnancy?
The main task of hCG during pregnancy is supporting progesterone production until the placenta develops enough to provide sufficient amounts of progesterone on its own.
That is necessary for a healthy pregnancy course. It ensures the development of cells in the uterus, prevents cramps and consequent miscarriage, and prepares the breasts for milk production.
Pregnancy tests and hCG hormone
The hCG pregnancy hormone produces in a woman’s placenta. It starts forming right after conception, after a fertilized egg implants in the uterus. The hormone reaches its peak in the first 8-11 weeks of pregnancy, then its volume slowly stabilize.
Pregnancy tests can tell whether you are pregnant by detecting an hCG pregnancy hormone in your blood or urine. And, because it starts forming so soon, you can get a positive result in such an early pregnancy, usually immediately after the absence of the period.
Blood vs. urine pregnancy test and hCG:
The results are pretty accurate, however, there are minor differences between blood tests and urine-based home pregnancy tests.
How soon can hCG be detected in blood after conception?
A blood test can detect the hCG pregnancy hormone earlier than a urine test. It can confirm or rule out pregnancy as soon as seven days after conception. It gives a positive result if it detects 5 mIU/ml (milli-International Units per milliliter) of hCG in the blood, wherein its accuracy is between 98 to 99%.
A blood hCG hormone test is commonly used by health care providers to confirm the results of a home pregnancy test.
There are two types of blood pregnancy tests:
- A qualitative hCG test, which checks whether or not the pregnancy hormone, hCG, is present. Its accuracy is about as accurate as a home urine test.
- A quantitative hCG test (beta hCG test), which measures the exact amount of hCG in the blood. It can detect even a trace of hCG, so it is a very accurate test!
A beta blood test measuring hCG levels in the later pregnancy can also show how well your pregnancy is progressing, including your baby’s development.
You can find everything about average levels of hCG in a pregnant woman’s blood further in this article.
How soon can hCG be detected in the urine for the results of the home pregnancy test?
The hCG value in the urine is sufficiently elevated for a positive home pregnancy test between the eighth and 14th day after you conceive. That means it can find the hCG hormone about a week after you’ve missed a period.
While a positive home test is almost certainly correct, is its negative result less reliable. Doing the test too soon can be a false negative. Wait at least about a week after your missed period, and if you still think you might be pregnant, do the test again or speak to your GP.
hCG blood levels
The hCG level usually doubles every 72 hours or every three days. Its highest level is between the eighth and 11th week of pregnancy, then it begins slowly decreasing and eventually stabilizes.
hCG levels vary from pregnant women to pregnant women, so its content in the blood does not determine gestational age. However, it shows the development of pregnancy and can be an indicator of possible problems.
Monitoring hCG levels don’t provide a diagnosis of anything. Unusual pregnancy hormone levels only suggest that there might be an issue and that your doctor should make additional tests.
What a particular hCG level in early pregnancy mean?
- Low levels of hCG in the blood (below 5 mIU / mL) indicate the high risk of miscarriage.
- Results between 6 and 24 mIU / mL are considered as an uncertain pregnancy. In such a case, it is necessary to wait if the value rises or falls over time. It usually takes two to three days before retesting.
- Anything above 25 mIU / mL is considered a positive pregnancy.
- Higher hCG levels in early pregnancy usually indicate that there is more than one fetus.
Average hCG’s levels in a pregnant woman’s blood:
|Week from the last menstrual period|
|Amount of hCG in mIU/ml|
|3||5 – 50|
|4||5 – 426|
|5||18 – 7,340|
|6||1,080 – 56,500|
|7-8||7, 650 – 229,000|
|9-12||25,700 – 288,000|
|13-16||13,300 – 254,000|
|17-24||4,060 – 165,400|
|25-40||3,640 – 117,000|
- non-pregnant women – less than 5 mIU/ml
- borderline pregnancy result – 6 to 25 mIU/ml
- positive pregnancy test – more than 25 mIU/ml
Frequently asked questions about pregnancy hormone hCG
What does a low hCG level mean?
If your blood test shows a low hCG level, don’t panic right away. It can mean several things and should be rechecked after a week.
It may have been just a miss calculation of your due date. But unfortunately, a low hCG level often indicates more severe problems, such as possible miscarriage, ectopic pregnancy, or a blighted ovum.
What does a high pregnancy hormone level mean?
A high level of hCG can also mean that your due date was miscalculated. Other possible reasons for a high hCG level are also a molar pregnancy or multiple pregnancies.
Should your doctor check your hCG level regularly?
No. Doctors usually check your hCG levels only if you are showing signs of a potential problem.
Your gynecologist will monitor your hCG levels more closely if you experience bleeding during pregnancy, if you have severe cramps, or if you have had miscarriages in the past.
Can something interfere with hCG levels and cause a false pregnancy test result?
Pregnancy tests are very accurate, so as I already wrote before, a positive test result probably means you are pregnant. There might be a false negative result if you have done your pregnancy test too soon. Remade it after a week, just to be sure.
However, although extremely rare, few situations may cause a false positive pregnancy test. These are an early miscarriage, certain types of cancer, and some medications.
What medications affect hCG levels?
- Hormone medications, such as contraception, should not have any impact on pregnancy hormone levels. The same goes for antibiotics and pain relievers.
- Medications for infertility treatments contain hCG and may interfere with hCG levels.
- Antihistamine Promethazine, in combination with other allergy medications, can increase or decrease hCG levels.
- Diuretics can also cause false low hCG levels in urine test results.
Talk to your doctor if you use one of the following medications:
- anticoagulant to prevent blood from clotting
- prescription sleep medications, such as Ambien or other hypnotics
- antinausea tablets, such as Prochlorperazine
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