hCG Pregnancy Tests: Are They Accurate & How to Read Results
If you’ve ever taken an over-the-counter pregnancy test before, you have tested for the presence of hCG in your urine. That’s because once implantation occurs, hCG is produced at a rapid rate – making it the key hormone used to detect early pregnancy.
But how accurate are these at-home pregnancy tests really? And when should you have your hCG tested at your doctor’s office?
In this article, we will be taking a closer look at what hCG is, what an hCG pregnancy test is, and how to interpret your results. We’ll also cover some of the most frequently asked questions regarding the accuracy of hCG tests, what hormonal hCG levels look like in a typical pregnancy, and the potential risks associated with using an hCG pregnancy test.
What is hCG?
Human chorionic gonadotropin (abbreviated as hCG) is a type of pregnancy hormone that rises rapidly in early pregnancy. The purpose of hCG is to help the corpus luteum ramp up the production of progesterone. This not only supports the growth of the uterus and uterine lining, but it also helps to prevent early contractions.
Measuring hCG is one of the primary ways to test for pregnancy. In blood, the hormone can be detected as early as one week after fertilization. In urine, it can be detected around 12-15 days after ovulation.
How does an hCG pregnancy test work and when is it used?
There are a number of different ways that you can test for the presence of hCG. Here’s a look at the types of tests available and the best times to use them.
Urine testing for hCG
Urine hCG tests are normally available as either strips of paper, or as single sticks made of plastic. These tests are designed to test whether or not your hCG levels are above the threshold for early pregnancy, which is typically above 5-25 MIU/ml.
To use these tests, you will need to collect a urine sample and wait for the test result. Paper strip tests and some plastic tests will display your results as either a single line (meaning you are not pregnant) or as two lines (meaning you are pregnant). For plastic tests with a digital display, you may also receive your results displayed as either a “yes or no” answer or as the words “pregnant or not pregnant”.
When it comes to timing, the best time to take a urine pregnancy test is on the first day of your missed period (or around two weeks after ovulation). If taken before, you risk receiving a false negative result.
The main perk of an hCG urine test is that you can receive your results within around 5-15 minutes. They are also private, convenient, and can be relatively cost-effective if you use the basic paper strips.
Blood testing for hCG
In addition to urine testing, your doctor can also use a blood test to measure the amount of hCG in your body. All you have to do is go to your doctor’s office, give a blood sample, and wait to receive your results.
The main benefit of blood testing for hCG is that you will be able to receive your numeric hCG level, which is not possible with typical at-home urine tests. This information is particularly useful for women who have experienced a miscarriage or miscarriages in the past, or for those currently undergoing fertility treatment.
Another benefit is that hCG is detectable in blood before it can be detected in urine. Therefore, blood tests can be taken as early as one week after conception.
How do you read hCG pregnancy test results?
It’s completely normal to feel confused or overwhelmed about interpreting your pregnancy test results. Here’s a quick look at the basics.
What do positive results look like?
A positive pregnancy test can look like any of the following:
- Two lines (it’s okay if one line is lighter in color than the other)
- The word “yes” or “yes+”
- The word “pregnant”
A positive result indicates that there is a high possibility that you could be pregnant. If this is the case for you, it’s a good idea to take at least one more test to confirm your result.
You should also consider doing the following:
- Switching to a healthy pre-pregnancy diet
- Taking a daily prenatal vitamin
- Avoid consuming tobacco, alcohol, and drugs
You should also make an appointment with your doctor immediately so that they can confirm your result with a blood test, provide further guidance on starting your pregnancy journey, and answer any questions you may have.
What do negative results look like?
A negative result will look like:
- One line only
- The word “no”
- The words “not pregnant”
If you have received a negative result and are actively trying to conceive, there is still a possibility that you are pregnant but that it is too early to tell. In this case, try to stay patient and take another test in a few days.
Are the results accurate?
When used correctly, at-home pregnancy tests can be up to 97% accurate. However, there are certain factors that can influence their accuracy.
What could impact the results?
The main factor that can impact the results of your pregnancy test is timing. According to the Food and Drug Administration (FDA), approximately 10-20 out of every 100 pregnant women will be unable to “detect their pregnancy on the first day of their missed period”. This is because they either have irregular periods, or they calculate their estimated period date incorrectly.
Even though it’s tempting to want to test as soon as possible (especially if you are actively trying to conceive) it’s important to wait to test at the appropriate time to avoid the disappointment of a false negative. To ensure you receive the most accurate results, make sure to test either:
- One week after your estimated fertilization date with a blood test, or
- 12-15 days after your day of ovulation with a urine test.
Medication is another potential factor that may interfere with the accuracy of your results. For example, if you are undergoing fertility treatment and are taking medication containing hCG, this may cause you to receive a false positive result.
In addition to timing and medication, there are other potential reasons why you may receive a false positive or false negative result. This includes:
- In cases where a chemical pregnancy has occurred
- If a miscarriage has happened recently
- If you have recently had an abortion
Last but not least, simple user error can be blamed in many cases. That’s why it’s important to always read and follow the instructions of your pregnancy test thoroughly.
If you have received a positive urine test result, or if you have received a negative result but are experiencing early pregnancy symptoms, it’s a good idea to make an appointment with your doctor and take a blood test. This will help to confirm for sure whether or not you are pregnant.
hCG pregnancy test FAQs
If you are still a bit curious about hCG and its role in pregnancy, here are a few of the most frequently asked questions answered.
What are normal hCG levels in pregnancy?
HCG levels can vary greatly depending on the individual. However, they do typically fall within the following ranges at each stage of pregnancy:
- hCG levels at 3 weeks: 5-50 mIU/ml
- hCG levels at 4 weeks: 5-426 mIU/ml
- hCG levels at 5 weeks: 18-7,340 mIU/ml
- hCG levels at 6 weeks: 1,080-56,500 mIU/ml
- hCG levels at 7-8 weeks: 7,650-229,000 mIU/ml
- hCG levels at 9-12 weeks: 25,700-288,000 mIU/ml
- hCG levels at 13-16 weeks: 13,300-254,000 mIU/ml
- hCG levels at 17-24 weeks: 4,060-165,400 mIU/ml
- hCG levels at 25-40 weeks: 3,640-117,000 mIU/ml
- hCG levels if not pregnant: 0-5 mIU/ml
Figures from The American Pregnancy Association.
In cases where hCG is higher or lower than these ranges, doctors may want to run further testing to monitor the health of the pregnancy. For example, if hCG is too low, this could be a sign of an ectopic pregnancy or miscarriage. If hCG is too high, this could indicate a molar pregnancy, down syndrome, or a multiple pregnancy.
More information about hCG levels can be found in our recent article: hCG Levels by Week: Normal Pregnancy hCG Levels Chart
What does hCG intact mean?
There are several forms of hCG that are present in both the blood and urine. “Intact hCG” is one of the forms, and it is secreted predominantly in early pregnancy by the emerging placenta. The majority of pregnancy tests are designed to detect this specific variant of hCG, given its prevalence in early pregnancy.
Can hCG levels be wrong?
If your hCG levels are too high or too low for where you think you are in your pregnancy, this could mean that you have miscalculated your conception date.
For example, if they are higher than where you believe you are in your pregnancy, your conception date may actually be earlier than what you previously calculated. Alternatively, if they are lower than where you think they should be, there is the possibility that you are not as far along in your pregnancy as you anticipated.
If you are worried about your hCG levels and the progress of your pregnancy, speak to your doctor and they can ease any concerns or conduct further testing.
Are hCG pregnancy tests accurate?
In general, hCG pregnancy tests are accurate. All at-home urine tests endure rigorous testing in order to be approved for use by the FDA, and all blood tests at your doctor’s office are administered and analyzed by qualified medical professionals.
When comparing the two types of tests, it is important to note that at-home urine hCG tests have the potential to be much less accurate than blood tests. This is because the accuracy of at-home tests can depend on a few factors. This includes:
- How well you understand and follow the instructions – for example, in cases where the test kit is mishandled or if the urine sample is not collected properly.
- How you interpret the results – test results that are displayed as either one line or two lines can be confusing for many.
- The timing of your test – if the test is taken too early, hCG may not be detectable in a pregnancy test yet – even if a pregnancy has occurred.
- Which medications you are taking – certain fertility medications may cause a false positive result.
- Medical history – for example, if you have recently had an abortion, miscarriage, or if you have a medical condition that impacts fertility, such as polycystic ovarian syndrome (PCOS).
Blood tests, on the other hand, are 99% accurate and can detect lower concentration levels of hCG compared to urine tests. Another perk of hCG blood testing is that they can measure your exact hCG concentration levels, measured in MIU/ml. This is called a quantitative hCG blood test.
Are there any risks with using a hCG pregnancy test?
There are no risks to your health and safety associated with using an hCG pregnancy test.
However, there is the risk of receiving a false positive or false negative result.
If you receive a false positive result, this means the test will say you are pregnant even though you are not. This could potentially cause emotional distress after learning from your doctor that a pregnancy has not occurred. To avoid this false sense of hope after receiving a false positive, always wait until you have confirmation from your doctor that you are in fact pregnant before celebrating or telling others outside of your immediate circle.
If you receive a false negative result, this means the test will say that you are not pregnant even though you are. In this case, a pregnancy may be at risk if you do not take the appropriate care and caution in early pregnancy.
Whether you are actively trying to conceive or not, if you are having unprotected sex with your partner there is the possibility that you could become pregnant. Regular hCG testing and check-ups with your doctor will help to prevent surprises and set up a potential pregnancy on the right track.