These things can be really confusing, especially if you’re already anxious about whether or not you’ve fallen pregnant. Basically, a blood test done by a doctor is the best way to find out if you are actually pregnant. It is the most accurate test you can do, it’s completely safe and your doctor will be on hand to advise you once the results are ready.
Now there are two kinds of tests that your doctor can do – a qualitative and a quantitative test. Both look for the presence of hCG in the blood. However, the qualitative test only checks to see whether or not hCG is present, while the quantitative version looks to see how much of the hormone is present.
The second option, also known as a beta-hCG test, is also far more sensitive and can detect even trace amounts of hCG in your blood. This means that you can try this test a lot earlier in your pregnancy and potentially still get a result. This is the test that gynecologists will do if you’ve been artificially inseminated and they want to check to see if the embryos have implanted.
So what exactly is hCG?
This is often referred to as the pregnancy hormone because it is only released into the body once an embryo is implanted into the uterus wall.
hCG is measured in thousandth international units per milliliter, which is shown like this: mIU/ml. This is the amount of the hormone found per ml of blood analyzed. With a quantitative test on your blood serum, you can get a reading as low as 5mIU/ml. This enough to be considered positive for pregnancy.
If you get a qualitative blood test done, the levels usually have to be above 50mIU/ml in order to be considered definitively positive. Some can read as low as 25mlU/ml, but anything lower is considered indeterminate. You will then have to wait a couple of days and take the test again to confirm the result. The good news is, levels of hCG increase very rapidly in the first part of a pregnancy, so another 48 hours should be sufficient to get the levels high enough for a reading.
Levels of hCG can vary quite significantly from pregnancy to pregnancy, so it’s difficult to say exactly what your levels should be at each stage. This table from Lavoisier and Delboni shows the wide variations you can expect, as well as the exponential increase in hormone levels that are quite common.
| 3-4 weeks | 9 – 130 |
| 4-5 weeks | 75 – 2600 |
| 5-6 weeks | 850 – 20800 |
| 6-7 weeks | 4000 – 100200 |
| 7-12 weeks | 11500 – 289000 |
| 12-16 weeks | 18300 – 137000 |
| 16-29 weeks | 1400 – 53000 |
There are many tables with this information available online and in medical journals. However, your doctor will be able to tell you if you are within the normal ranges and if things are progressing well.
When should you take a pregnancy test?
In order to avoid getting an indeterminate or false result, it’s important to take a pregnancy test at the right time. Always consider these factors:
- Your menstruation should be at least two days late before you consider taking a pregnancy test.
- If you’ve had fertility treatments using hCG, it’s best to wait a little longer before taking the pregnancy test.
- If your cycle is irregular, wait for the longest time period your cycle has been in recent months.
You can book an appointment for your doctor to take blood for either a qualitative or a quantitative test at any time. You do not need to fast before the blood is taken, and it can be done at any time of day.
Recurring questions from readers
We receive many similar questions when it comes to blood tests to check if you’re pregnant. Here are the top questions and their answers to help you out.
Can a beta-hCG test give a false result?
While this is the most reliable test you can take, it is possible to get a false negative with it. This only happens if you take the test too early and haven’t given the hCG being produced by your body enough time to build up to sufficient levels. This is why it is always best to wait until you are sure your menstruation is more than a couple of days late. If you get a negative result but still think you are pregnant, wait another few days and try again.
Can you determine gestational age from the level of hCG in the blood?
The levels of hCG aren’t the most reliable way to work out how many weeks pregnant you are. The levels can vary so dramatically from one pregnancy to the next. They also increase exponentially, which means there could be a big difference every 48 hours in the beginning.
Most doctors will rather count from the date of your last menstruation. This will give them the likely day that you ovulated and when you would have conceived according to this. However, your cycle could have been longer or shorter this time around, which means that determining gestational age this way isn’t completely accurate.
The best way to determine gestational age is through an ultrasound. Your doctor will indicate when they will be able to tell you this information for sure.
Can you use a test from a pharmacy instead of a blood test?
It’s highly advisable that you go to your doctor and get a proper blood test done to confirm whether or not you are pregnant. Pharmacy tests are great to give you quick peace of mind, but it’s important to remember that they aren’t always reliable or accurate. A blood test analyzed by a doctor is far more sensitive than any pharmacy test, and gives you a completely reliable answer.
What does it mean if the test shows a low amount of hCG in the blood?
There are two reasons for the levels of hCG to be very low on the test results. The first is that your pregnancy is very early and your body hasn’t had enough time to build up the hormone yet. The other reason could be a chemical pregnancy. This is when you have a spontaneous miscarriage in the early weeks of a pregnancy. The egg was fertilized and implanted, but for some reason was not viable to continue growing.
When you get a low reading on a test, it’s best to wait a few days and try the test again. If the levels remain the same or decrease, you are not pregnant. However, if the levels have gone up quite a bit, you are pregnant.
It is best to take the quantitative or qualitative test?
Your doctor will tell you which option is the best for you to take, depending on your specific situation. The qualitative test gives you a clear positive or negative result. The quantitative test, on the other hand, will show how much of the hormone has built up in your system and can assist with showing the progression of your pregnancy.
Are quantitative and qualitative tests reliable?
Yes, all tests done through analysis of the blood are completely reliable. The only time you may have a problem with the result is if you take the test too early.