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Getting an hCG blood test soon? Or trying to understand your test results?
An hCG blood test tells you how much human chorionic gonadotropin (hCG) is in your blood. They’re more accurate than urine hCG tests because they give you a quantitative result (an exact hCG value). They can also detect even the smallest amounts of hCG.
In fact, some research shows that trace amounts of hCG can show up in a pregnant person’s blood as early as 6–8 days after fertilization. But there’s a lot more to know about how hCG blood tests work. So keep reading for a deep dive into hCG, the purpose of hCG blood tests, and what hCG values indicate!
Key takeaways
- An hCG blood test can detect pregnancy through both qualitative and quantitative results.
- An hCG blood test only shows you one aspect of the larger picture of your pregnancy health.
- A single hCG test result doesn’t definitely show whether a pregnancy is developing normally or not.
- hCG levels can differ a lot from one pregnant person to another (or one pregnancy to another).
- Other diagnostics like ultrasound and repeat hCG tests can be used in cases where results are unclear.
- If you have concerning symptoms like bleeding or dizziness while pregnant, contact your doctor regardless of what your hCG test result says.
What is hCG and its role?
You may know of human chorionic gonadotropin (hCG) as the “pregnancy hormone.” This is because it’s popularly used to confirm pregnancy and assess the health of a pregnancy.
hCG production starts with specialized cells within the embryo prior to implantation. Then once implantation is successful, the developing placenta will take over producing hCG. The main role of hCG in early pregnancy is to maintain the corpus luteum, the structure that develops from the ruptured ovarian follicle after ovulation. This is vital since the corpus luteum is responsible for producing another essential pregnancy hormone: progesterone.
Beyond the basics
hCG is a bit more complex than most people realize! This pregnancy hormone comes in several forms that are produced by different types of cells at various stages of pregnancy. And each form has its own distinct role to play.
A bit confusing? Here’s an example of what we mean:
The regular version of hCG most people think of is the one responsible for keeping early pregnancy running smoothly. But there’s another version called hyperglycosylated hCG. This type supports implantation and helps with the creation of the placenta. Even though these two types of hCG have different roles, they’re both referred to as hCG. The main reason for this is the fact that they have the same basic protein structure. hCG has two subunits: alpha and beta. The alpha subunits look exactly the same as the alpha subunits of other hormones like LH (luteinizing hormone), FSH (follicle-stimulating hormone), and TSH (thyroid-stimulating hormone). The beta subunits are what distinguish hCG from those other hormones.
Most of the blood hCG tests and urine tests out there detect beta hCG. Otherwise, you would get inaccurate results from the alpha subunits of various hormones being detected. But let’s look more closely at how hCG blood tests in particular work!
What are hCG blood tests, and how do they work?
As the name suggests, an hCG blood test measures hCG in a given blood sample. But not all hCG tests are the same. Some are quantitative. Others are qualitative.
- A qualitative hCG test tells you whether or not hCG is present. This is the type you’ll see with most at-home hCG blood and urine tests.
- Quantitative hCG tests are different. They tell you exactly how much hCG is present. This is the type you’ll see when you do an hCG blood test through a laboratory.
Blood pregnancy tests involve laboratory analysis and can pick up on hCG levels as low as 1–5 mIU/mL. This is because beta hCG will appear in your blood supply before it reaches a concentration high enough to detect in your urine. (Hence you can detect pregnancy sooner with a blood test than you can with a urine test!)
Regardless of using a serum (blood) hCG test or a urine hCG test, hCG will nearly double about every 48 hours. This goes on until up until the 8th through 10th week of pregnancy.
Know more : hCG Doubling in Pregnancy: Why It Matters
In case you’re wondering the exact ways that urine and blood hCG tests differ, see the next section for a quick comparison!
What’s the difference between blood hCG tests and urine hCG tests?
There are many differences between these two hCG test types! Look at the table below to see an overview of how they measure up.
Blood hCG test | Urine hCG test | |
Sample comes from | Blood | Urine |
Who examines it | Laboratory | You |
Pregnancy test type | Quantitative (lab-based) or qualitative (for mail-in or at-home tests) | Qualitative |
Sensitivity | Higher | Lower |
Best day to test | Within a few days after implantation, labs can detect hCG values as low as 1-5 mIU/mL | From the first day of a missed period, usually 12 – 14 days past ovulation (DPO). |
Best time of day to test | Any time of day | First morning urine is best |
Affected by fluid intake? | No | Yes (diluted urine can increase chances of a false-negative) |
Accuracy | Lab blood tests highly accurate; even self-collected samples have been reported to be nearly as accurate (though larger studies are still needed) | Around 99.2% when used according to manufacturer’s directions |
If you plan to go ahead with an hCG blood test, you’re probably wondering what steps are involved. We’ll take a look at this next!
How is an hCG blood test performed?
There are two main ways to get an hCG blood test: through a laboratory or with a home test kit:
A laboratory hCG blood test involves:
- A blood sample taken at a lab (usually from a vein)
- No special preparation
- Exact hCG values
A home hCG blood test is a bit more involved. Here’s the gist of how a home blood test works:
- Prick your fingertip to collect a blood sample (usually with a lancet)
- Put the sample on the testing device
- Read the result based on the parameters spelled out on the manufacturer’s instructions
With home tests, it’s always important to read the directions carefully. The exact instructions may differ slightly from one test brand to another. Some brands even provide mail-in hCG tests. For these blood tests, you collect the blood sample at home and then mail it to a certified laboratory. At the lab, certified lab professionals will measure the exact value of beta hCG.
One study found that these self-collected blood samples are a quality alternative to traditional blood draws at a lab. This is great news as these tests could be a more accessible option for those who may find it difficult to get to a laboratory. Keep reading to understand the main reasons for getting a blood hCG test.
When is an hCG blood test performed?
hCG blood tests can be used for pregnancy- and non-pregnancy-related reasons.
hCG blood tests for pregnancy-related cases
In the case of pregnancy or suspected pregnancy, a beta hCG blood test is helpful when:
- The patient needs to confirm their pregnancy very early on
- A home pregnancy test result is unclear
- The pregnant person is experiencing vaginal bleeding or pelvic/abdominal pain
- There’s no clear timeline as to the dating of the pregnancy
- A miscarriage or ectopic pregnancy is suspected
- A series of hCG tests are needed to see hormone progression over time
- The patient’s hCG levels are being monitored after a loss or ectopic pregnancy
When it comes to a healthy pregnancy, the exact hCG value and the progression over time both matter. Studies show that when beta hCG is low or rising slowly, there’s a higher risk of early pregnancy loss. One study puts this into perspective. According to an 8-week ultrasound, 22 out of 158 pregnant women with slower-rising hCG had a viable pregnancy. After the first trimester though, only 16 out of those 22 pregnancies were actually viable.
The following hCG markers are often a sign of a poor embryo development or a non-viable pregnancy:
- Lower hCG concentrations in the beginning
- hCG values that increase slowly
- Levels that plateau
- Levels that decrease over time
Know more : Pregnant But hCG Rising Slowly: What to Know
hCG tests for non-pregnancy cases
Most people don’t know that hCG testing isn’t only about pregnancy. Outside of pregnancy, hCG blood tests are helpful for monitoring:
- Testicular germ cell tumors
- Ovarian germ cell tumors
- Gestational trophoblastic disease (rare tumors that start from the abnormal cells within the placenta). It can lead to a molar pregnancy and choriocarcinoma (a type of cancer that usually begins in the uterus).
Other cancers like breast cancer, cervical cancer, and others may also be indicated with an hCG blood test. But these are less common instances. In these cases, evaluating serum hCG levels is helpful for:
- Diagnosing the severity of the disease
- Keeping track of treatment effectiveness
- Checking for recurrent disease
Regardless of the reason for getting an hCG test, it’s important to understand how to read the results. Keep reading to learn the basics of various types of hCG test results.
How to read the hCG blood test results?
The way you read your hCG test depends on the type of test you’re using.
Home blood hCG tests (qualitative tests)
Remember, a qualitative hCG test can only tell you whether or not your hCG levels pass a certain threshold. They don’t actually give you a numerical value.
Here’s how these test results are usually interpreted:
- The control and test lines appear = positive
- Only the control line appears = negative
- No control line appears = test is invalid
These types of tests are often used to see if hCG is high enough to confirm pregnancy.
Lab hCG tests (quantitative tests)
Different laboratories may have various ranges of hCG reference levels. But the ranges below give you a general idea of what different hCG values indicate:
- A non-pregnant woman: below 5 mIU/mL
- A pregnant woman: above 25 mIU/mL
- Indeterminate (may need a repeat test): 5 – 25 mIU/mL
Keep in mind that hCG levels increase fairly rapidly early on in pregnancy. Look at the chart below to see the standard blood hCG values based on gestational age. (Note: these values should be viewed as a general reference. Exact hCG levels can vary quite a bit from woman to woman.)
Week of Pregnancy | hCG Blood Levels (mIU/mL) |
3 | 5-72 |
4 | 10-708 |
5 | 217-8,245 |
6 | 152 – 32,177 |
7 | 4,059 – 153,767 |
8 | 31,366 – 149,094 |
9 | 59,109 – 135,901 |
10 | 44,186 – 170,409 |
As you can see above, hCG levels steadily rise from one week to the next. That said, by the 10th week of pregnancy, hCG levels usually reach their peak.
For some women, hCG levels may even begin to drop around week 16. From there, hCG will stay around the same level for the rest of the pregnancy. Levels for the 2nd and 3rd trimester are usually in the range of 20,000 – 200,000 mIU/L.
Curious to know what happens with your hCG levels after pregnancy?
After delivery or a miscarriage, hCG levels fall rapidly and then slow down. It usually takes up to 3–4 weeks for hCG to fall back down to baseline levels.
There are two exceptions to this:
The first is if your hCG was exceptionally high during pregnancy (as in the case of a multiple pregnancy). Then it may take a little longer to return to baseline hCG levels.
The second case is if some of the placental tissue is still inside. This would require follow-up with your doctor to remove the remaining tissue and rule out gestational trophoblastic disease.
Worried about an abnormal hCG result? Keep in mind that an hCG result is only one part of the picture. And there are a few reasons that could lead to hCG levels falling outside the norm. More on this next!
What do abnormal hCG blood test results mean?
Scenario 1: Higher hCG levels
This scenario can happen in the following cases:
- A twin or multiple pregnancy
- A recent abortion or miscarriage
- Rare pregnancy-related conditions like molar pregnancy and choriocarcinoma
- Certain cancers
Scenario 2: Lower hCG levels
This scenario can happen during:
- Very early pregnancy
- Pregnancy loss
- Incomplete miscarriage
- Threatened spontaneous abortion
- Ectopic pregnancy
We know it can be alarming to think about having a miscarriage. But keep in mind that a single hCG test result doesn’t mean that you definitely have one of these conditions. It all depends on your gestational age and any additional testing your doctor does. But in case you’re wondering what else could be impacting your hCG levels, keep reading!
What factors affect hCG levels?
The hCG levels chart we provided earlier gives a helpful reference point. But hCG levels can vary greatly from one pregnancy to another. That’s why your healthcare provider will look at other data points like your gestational age, rate of hCG rising, ultrasound, and symptoms. On top of that, there are other factors that can impact your exact hCG levels.
These include:
- The type of laboratory method used
- BMI (a higher BMI is linked to lower circulating hCG levels early on in pregnancy).
- Smoking (smoking is associated with lower pregnancy hCG concentrations)
- Ethnicity
- The number of previous pregnancies
- The weight of the placenta (Bigger placentas may produce more higher amounts of hCG)
- Severe nausea during pregnancy, aka Hyperemesis gravidarum (HG) (Women with HG usually have higher hCG levels)
- The baby’s sex (pregnancies involving a female fetus seem to have slightly increased hCG levels)
Despite these factors, if you’re worried about your hCG results, it’s important to seek medical attention.
When to contact your doctor about your hCG levels?
Here are some reasons you’ll want to see your doctor about your hCG levels:
- Your hCG is increasing slowly
- Your levels are dropping or changing unexpectedly.
- You have bleeding or pelvic pain during early pregnancy (even if your hCG levels appear normal)
- You get a positive hCG result but an ultrasound hasn’t officially confirmed pregnancy location
We know that hCG testing for any reason can feel confusing and overwhelming at times. One of the most important things to remember is to not make any assumptions based on your hCG alone.
Talk to your doctor, keep track of your other symptoms and gestational age, and seek additional testing like an ultrasound or follow-up hCG test. And if you want to feel less alone in your hCG testing or fertility journey, join Inito’s fertility support group!
FAQs
An hCG blood test tells you how much human chorionic gonadotropin (hCG) is in a blood sample. This information can usually tell you if you’re pregnant and how far along. It can also help indicate other health conditions like the presence of certain types of tumors.
In a non-pregnant person, normal hCG levels are less than 5 mIU/mL. During a pregnancy normal hCG levels depend on the week of pregnancy.
Know more: What is a Positive Beta hCG Blood Test?
A positive hCG level for pregnancy is usually above 25 mIU/mL but the exact level will depend on the gestational age. Here are the standard ranges for hCG during early pregnancy:
- 4 weeks: 10 – 708 mIU/mL
- 5 weeks: 217 – 8,245 mIU/mL
- 6 weeks: 152 – 32,177 mIU/mL
- 7 weeks: 4,059 – 153,767 mIU/mL
Keep in mind these are general ranges, and hCG pregnancy levels vary a lot from person to person!
A blood hCG test can usually come up positive within several days after implantation. This is because detectable amounts of hCG show up in your blood stream sooner than they do in your urine.
To confirm pregnancy with an hCG test, you need to understand the type of test you’re using. If you use a urine test, you’ll want to wait to test until your missed period. The urine test will give you a positive or negative result based on whether your hCG levels reach a certain threshold (usually around 20 – 25 mIU/mL). If you do a blood test at a lab or with a mail-in test kit, you will get a numerical value. Values above 25 mIU are generally considered positive for pregnancy.
An hCG blood test measures how much human chorionic gonadotropin is present in your blood. You can do hCG blood tests at a laboratory. But nowadays, you can also do them with home test kits and mail-in test kits.
Blood hCG tests are generally reliable, but no test is 100% accurate. A result can sometimes be affected by laboratory or biological factors. And a single hCG value may not provide enough information to determine how a pregnancy is progressing. When needed, doctors may interpret hCG alongside symptoms, gestational age, ultrasound findings, or repeat hCG measurements.
The blood draw itself usually takes only a few minutes. How long it takes to receive the hCG result depends on where the test is performed and the type of test used.
An hCG value of 1.20 mIU/mL is considered negative for pregnancy. In general, a positive hCG value is above 25 mIU/mL (in terms of pregnancy confirmation).
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