One of the most important things to know if you are confused about when you should take a home pregnancy test is that you are more likely to get a negative result if it’s done too early.
How Does a Pregnancy Test Work?
Before going further, it will be helpful for you to understand how a pregnancy test works in order to know when to take one.
Pregnancy tests are made to detect human chorionic gonadotropin or the hCG hormone in the urine or blood. This is a pregnancy hormone that’s produced once a fertilized egg is attached to the uterus wall, usually starting around six days after the egg fertilization.
The hCG levels will continue to increase rapidly if you are pregnant, doubling every two to three days.
It is important to mention that there are some tests that are able to detect hyperglycosylated hCG or H-hCG, a variation of the hCG hormone.
The regular hCG is only produced after an embryo is implanted in the endometrium, while H-hCG is released earlier at some point right after fertilization.
When Should You Take a Home Pregnancy Test
You can get the most accurate result if you wait at least one week after missing your period. In addition, the result might be even more accurate if the test is done first in the morning as the urine is far more concentrated at this time. The urine-based home pregnancy tests offer about 97% accuracy.
This accuracy will depend on several factors such as how early the test is taken, if the instructions were followed closely, when ovulation occurred in the cycle, how early implantation takes place, and how sensitive the test is.
It is always best to take a pregnancy test after a late period to avoid false positive or false negative results.
If you have irregular cycles or you are not charting your cycles, it might best to take the test after passing the longest menstrual cycle.
For example, if your cycles are in the range of 30 to 36 days, it would be best to take the test at around 37 days after your last period or later.
How Soon After Sex Can You Take a Pregnancy Test?
Many women take a pregnancy test right after they have sex. This is actually a huge mistake because, as mentioned above, the levels of hCG in the body can be detected several days after the fertilized egg has been implanted in the uterus.
By taking the pregnancy test too early, it can result in a false-negative result and make you believe that you’re not pregnant.
So when is the right time to take a pregnancy test after having unprotected sex? According to experts, you can take the test 10 to 14 days after having intercourse since, during this time, the hCG levels in your body are already high enough to be detected.
Many home pregnancy test kits will include this fact in their instructions to ensure that users will get accurate results.
However, this 10-to-14 day time frame is only the minimum. If you’re not in a hurry, it’s advisable to wait for a longer time before you take a home pregnancy test.
Many experts recommend that you take the test 21 days after having unprotected sex for more accurate results .
This might seem like a long time to wait, particularly if you’re eager to get pregnant and want to know if you’ve conceived ASAP. But it’s important to note that conception doesn’t always happen right after you have sex.
Remember: sperm can live inside your body for up to five days, which means that fertilization can take place up to five days after you had intercourse. So, if you have sex a few days before ovulation, it can be difficult to pinpoint exactly when you conceived.
If the actual conception happened a few days after you had sex, but you decide to take a pregnancy test exactly 10 days after your intercourse, your body might not yet have produced enough hCG levels for the test to detect.
This might mean that you’ll get a negative result — even though fertilization did happen and your egg has implanted (or is about to implant) in your uterus.
So, to get accurate results, it’s best to wait for three weeks after having intercourse before you use a pregnancy test kit.
This is also the reason why you shouldn’t hesitate to take another pregnancy test even if you’ve already taken one.
If you get a negative result but genuinely believe that you are pregnant, take another pregnancy test around a week after you took the initial test.
By this time, fertilization and implantation might have already taken place, which means that the hCG levels are high enough for you to get an accurate reading.
If you get a negative pregnancy test few days after positive urine pregnancy test, you may have experienced a phenomenon called Chemical Pregnancy that accounts of 50-75% of all miscarriages. 
If you can’t wait for three weeks, you can visit your doctor and ask for a blood pregnancy test.
This test detects pregnancy earlier than urine-based home pregnancy tests since hCG appears earlier in the mother’s blood than in her urine.
You can take the blood pregnancy test at least eight days after you had unprotected sex  although, just like with home pregnancy tests, you can get more accurate results if you wait a few days longer after having intercourse.
Blood tests can detect pregnancies earlier than urine test because these tests can detect hCG levels as low as 1 mIU/mL, while urine test strips have published detection thresholds of 10 mIU/mL to 100 mIU/mL, depending on the brand. 
How Should You Take a Home Pregnancy Test?
Now that you have an idea as to when you should take a home pregnancy test, you need to know how to use it.
The home pregnancy tests are easy and quick to use. Once the instructions are followed carefully you will get accurate results.
They are all made to work in the same way. You’d use one of these ways to test your urine:
- Collect some urine inside a cup and then use a dropper to place it in another container.
- Collect some urine inside a cup and dip the pregnancy test stick in it.
- Hold the pregnancy test stick under your urine stream.
For all of these techniques, you’ll have to wait several minutes to see the results. The results can show as a color, line or symbol. Some digital tests will say not pregnant or pregnant.
What is The Meaning of the Pregnancy Test Results?
When you do the test and the result is positive, this means you are pregnant. Bear in mind that this will be the case, regardless of the faintness of the color, line or sign.
It would be a good idea to contact your doctor in order to know what will come next if you get a positive result.
A negative result will mean that you are not pregnant. Nevertheless, you could still be pregnant in cases where the test is taken incorrectly, the test stick is expired, the test is done too soon, you are using certain medications like antihistamines or diuretics, and large amounts of liquid is consumed immediately before the test (which dilutes the urine).
You could try retesting about one week after getting a negative result to get a more solid confirmation. There are some home-based pregnancy tests that will suggest this no matter the results.
Although this only happens in rare cases, a pregnancy test can give a false-positive. This means the test is saying you are pregnant, but you are not.
You could get this result if your urine contains protein or blood and if you are using certain drugs such as anti-convulsants or tranquilizers.
Be sure to contact your doctor if you have questions pertaining to the pregnancy test or results.
- Chemical pregnancy facts: https://www.healthline.com/health/pregnancy/chemical-pregnancy
- Waddell, Rebecca Smith (2006). “FertilityPlus.org”. Home Pregnancy Test hCG Levels and FAQ. Archived from the original on 2006-06-15. Retrieved 2006-06-17.