How long does it take before a pregnancy test works

If you think there is a chance you might be pregnant, you may be wondering when you can take a pregnancy test.

Table of Contents Show

Home pregnancy tests
How pregnancy tests work
Pregnancy tests that your doctor may do
Pregnancy tests and accuracy
What if the result is positive?
How accurate are home pregnancy tests?
What can cause a false-positive pregnancy test result?
What tests are done to confirm pregnancy?
When should you see a doctor?
Health News

You are more likely to get an accurate result if you wait until the day of your missed period or after. Some very sensitive pregnancy tests can be carried out as early as 8 to 10 days after conception (the day the pregnancy occurred).

You can take a pregnancy test at home. Your GP or GP practice nurse will also be able to perform a pregnancy test for you.

Home pregnancy tests

You can buy home pregnancy tests over the counter in your pharmacy. They are also sold in many shops and supermarkets. Read the instructions on the pregnancy testing kit before using it. The instructions that will tell you what the different colours or symbols mean.

How pregnancy tests work

Pregnancy tests detect the levels of a hormone called hCG in your urine (pee). This hormone is produced during pregnancy. It is present in your bloodstream and your urine.

In early pregnancy, the amount of the hormone in your system increases. The later you leave it to take a pregnancy test, the higher the hCG levels will be.

The earlier you take the test, the more likely you are to get a 'false negative' result. A 'negative' result is where the test shows up as negative even though you are actually pregnant.

Pregnancy tests that your doctor may do

Your GP will probably do a urine pregnancy test to detect whether you are pregnant.

It is always a good idea to bring a sample of urine to the GP surgery with you if you think you may be pregnant. This will mean your appointment is not delayed.

It will also avoid the 'stage fright' that can occur when you are trying to pee and you know someone is waiting on you.

The pregnancy testing kit that your GP will use is like the kits that you can buy over the counter.

Your doctor may perform a blood test to check the level of hCG in your blood. This test is done if you have had some bleeding from your vagina or if you have severe pains in your tummy. Your GP may also carry out a blood test if you have severe morning sickness.

Pregnancy tests and accuracy

A positive pregnancy test is almost always correct. Some negative tests may not be correct if you tested too early.

This is called a 'false negative' result. The result will present as negative, but you are actually pregnant.

This happens for a few of reasons, because:

you did the test too early
you didn't wait long enough before checking the result (always follow the instructions - it is normal for results to take 3 minutes to appear)
your urine is very diluted because you have been drinking a lot of water
there is a fault with the test

If the result of the test is negative, and you think you might still be pregnant, repeat the test a few days later. If symptoms persist after a few negative tests, make an appointment with your GP.

What if the result is positive?

A positive result generally means that you are pregnant. You should make an appointment to see your GP to confirm the pregnancy and to sign up for antenatal care.

If you are not sure you want to be pregnant it is good idea to make an appointment with your GP to discuss your options.

Your GP will listen and will not judge you.

Free advice may also be available from a family planning clinic.

Sometimes counselling can help you to work through your feelings about the pregnancy. It may help you make a decision on what is the right choice for you.

www.myoptions.ie has details of the support services available to you.

Accuracy
- How accurate are home pregnancy tests?
False-Positive Results
- What can cause a false-positive pregnancy test result?
Urine/Blood Tests
- What tests are done to confirm pregnancy?
When to See a Doctor
- When should you see a doctor?
Related Resources
- Related Resources - Early Pregnancy Test: How Soon Will a Pregnancy Test Read Positive?

An early pregnancy test can read positive as soon as 11-15 days after conception, 1 day after a missed period

An early pregnancy test can read positive as soon as 11-15 days after conception, 1 day after a missed period. However, more accurate results can be obtained 2 days after a missed period.

A home pregnancy test detects the presence of human chorionic gonadotropin (hCG), which is produced in a pregnant woman. Traces of hCG can be seen in urine 3-4 days after the fertilized egg implants in the uterus, and the amount doubles every 48 hours. When there is enough hCG in the body, a pregnancy test can detect it and produce a positive result.

If your periods are irregular, however, and your test result is negative, you should repeat a home pregnancy test after 1 week.

How accurate are home pregnancy tests?

Home pregnancy tests are quite reliable and usually 99% accurate. However, it is critical to carefully follow the instructions on the package.

It is recommended to test your urine in the morning since hCG levels will be at the highest concentration as soon as you wake up.
You can take the test at any hour of the day, but you need to keep your bladder full for at least 4 hours prior to the test.
Avoid drinking too much water before the test because it can dilute the hCG levels in your urine.

Here is how the tests work:

The test kits come with a test stick and a container that is used to collect the urine and transfer a few drops to the test stick.
If you are pregnant and there is sufficient hCG in your urine, the hCG in your urine reacts with the anti-hCG antibodies present in the test stick and inactivates them.
As anti-hCG bodies are inactivated, the stick indicates a positive pregnancy test.

What can cause a false-positive pregnancy test result?

In rare cases, a false-positive outcome can be caused by:

Blood or protein in your urine
Early miscarriage
Certain medications, such as tranquilizers, anticonvulsants, hypnotics, and fertility drugs

Other reasons for a false-positive result include:

Molar pregnancy: Also called a hydatidiform mole, a molar pregnancy is a benign growth that develops abnormally after an egg is fertilized. The placenta develops into an aberrant mass of cells and cysts. In rare cases, an embryo develops but is deformed and will not survive. In some cases, no embryo exists at all. Molar pregnancies can have serious complications and must be treated by a specialist.
Ectopic pregnancy: Ectopic pregnancy occurs when the fertilized egg implants in a location other than the uterus. In a tubal pregnancy, this occurs in one of the fallopian tubes that connects the ovaries to the uterus. However, the egg can sometimes implant in the abdominal cavity, ovary, or cervix. Because the fertilized egg cannot survive in these locations, the pregnancy cannot progress normally and the growing tissue can harm the mother's internal tissues, resulting in dangerous complications such as life-threatening blood loss. Early treatment of an ectopic pregnancy is critical.
Chemical pregnancy: Women who get early positive pregnancy test results but then get their period may have a chemical pregnancy. This is a situation in which the fertilized egg implants normally in the uterus, but only long enough to begin generating hCG. The egg then ceases growing for unknown reasons. This form of early miscarriage usually occurs when the fertilized egg has a flaw that prevents it from maturing normally. According to some experts, 20%-30% of all pregnancies end in miscarriage.

QUESTION

The first sign of pregnancy is most often: See Answer

What tests are done to confirm pregnancy?

In addition to false-positive results, a home pregnancy test may show a false-negative result, especially if you tested too early or if the kit was defective.

In order to confirm the results of a home pregnancy test, talk to your doctor to undergo additional tests. Your doctor may order urine or blood tests:

Urine tests: Urine is tested for the presence of hCG. A diluted sample may produce a false-negative result.
Blood tests: Blood tests are more sensitive than urine tests and can give an accurate result 9-10 days after conception. Blood test results not only confirm the pregnancy but can also diagnose a potential miscarriage. There are two types.
Qualitative test: Confirms the presence of the hCG hormone in the blood
Quantitative test: Measures the amount of hCG present in the blood.
- Higher hCG levels may indicate a multiple or twin pregnancy
- Lower hCG levels may indicate a miscarriage
- Slow rise of hCG levels may indicate an ectopic pregnancy

If pregnancy is confirmed, an abdominal ultrasound can be done to assess the development and health of the fetus.

When should you see a doctor?

Regardless of your pregnancy test results, consult your doctor if you develop any of the following symptoms:

Dizziness
Fainting
Abnormal vaginal bleeding
Severe, stabbing pain in the abdomen or on one side of the pelvis
No period even after multiple negative home pregnancy test results
Persistent pregnancy symptoms even after negative test results, such as:
- Nausea
- Breast tenderness
- Fatigue

If your home pregnancy test result is positive, you should see your doctor to both confirm the pregnancy and begin prenatal care.

Health News

Medically Reviewed on 3/8/2022

References

Image Source: iStock Images

American Pregnancy Association. What is HCG? https://americanpregnancy.org/getting-pregnant/hcg-levels/

Betz D, Fane K. Human Chorionic Gonadotropin. [Updated 2021 Aug 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022. https://www.ncbi.nlm.nih.gov/books/NBK532950

Memon N. How Soon Will a Pregnancy Test Read Positive? MedicineNet. https://www.medicinenet.com/how_soon_will_a_pregnancy_test_read_positive/article.htm