For a woman who wants to know whether she is pregnant or not, the most common way to confirm is through a pregnancy test. These tests are easy to use, accessible and can provide fast results.

With so many brands and types of pregnancy tests available in the market, it can be confusing to choose the right one. To understand how pregnancy tests work and how to use them, let’s discuss everything you need to know about the science behind pregnancy tests.

What is a pregnancy test?

A pregnancy test is a simple diagnostic tool that helps determine if a woman is pregnant, by detecting the presence of Human Chorionic Gonadotropin (hCG), a hormone produced during pregnancy.

The testing process involves collecting a urine sample or a blood sample and applying a chemical or a physical assay to detect the hCG hormone. A positive result indicates that the woman is pregnant, while a negative result indicates that she is not.

Types of pregnancy tests

Pregnancy tests are broadly categorized into two types: urine tests and blood tests. Within these categories, there are different brands and types of tests available.

Urine tests

Urine tests are the most commonly used pregnancy tests. These tests are affordable, easy to use, and can be done at home. Most urine tests are based on an antibody test. A strip of reactive antibodies is coated on a plastic strip.

The strip is then dipped into a sample of urine, and if hCG is present, it will bind to the antibodies, causing the strip to show a colored line, indicating a positive result. There are two different types of urine tests:.

Early detection tests

Early detection tests are highly sensitive and can detect pregnancy even before a woman misses her period. These tests can identify hCG levels as low as 10 mIU/mL, which is why they are also known as ultra-sensitive tests.

However, these tests are expensive compared to regular pregnancy tests, and their accuracy decreases if not used correctly.

Regular tests

Regular tests can detect pregnancy after a missed period and have a sensitivity of 25mIU/mL. They are affordable and easy to find at pharmacies. They are also sometimes offered at free clinics or as part of prenatal care packages.

Blood tests

Blood tests are typically done in a clinical setting and are more accurate than urine tests. A test that quantifies the amount of hCG in the blood is more accurate than a test that only confirms the presence of hCG in the blood.

A blood test can help detect hCG levels earlier than a urine test and often offers the most accurate results. Blood tests include two types:.

Quantitative blood test

A quantitative blood test measures the exact level of hCG in the blood. These tests are often used to determine the duration of pregnancy and the progress of a pregnancy.

They can also be useful in identifying whether a pregnancy is progressing as it should be.

Qualitative blood test

A qualitative blood test only confirms the presence of hCG. These tests are usually less expensive than the quantitative test and are often used to confirm pregnancy.

How to use a pregnancy test?

Most pregnancy tests are simple to use and have similar instructions. It’s essential to read the instructions carefully before taking the test, to ensure the best results. Here are some general steps for using a pregnancy test:.

Gather materials

You will need a pregnancy test kit, urine collection container, timer, and a clean, flat surface to conduct the test. Make sure the test kit is within its expiration date.

Collect urine sample

Collect your urine sample in a clean container. The first urine after waking up is the best for testing, as it has higher levels of hCG.

Conduct the test

Follow the instructions on the test kit. Usually, you will need to expose the test strip to urine or place urine in a small well in the test cassette.

Afterward, you will need to wait for a specified period, usually a few minutes, until the results appear. If you are using a digital test, the result will show up on the screen.

Read the results

Check the results after the specified waiting time. A positive result will display two colored lines or a plus sign. A negative result will show one colored line or a minus sign.

Factors that affect the accuracy of pregnancy tests

Pregnancy tests offer a high level of accuracy when used correctly. However, some factors can affect their accuracy, such as:.

Timing

The timing of the test can affect its accuracy. Pregnancy tests work best one week after a missed period, as hCG levels are likely to be at its highest. Conducting the test too early could result in a false-negative result.

However, this time frame can vary from woman to woman, and some tests may detect pregnancy even before the missed period.

Quality of the test kit

Ensure that you purchase a good quality pregnancy test kit from a reputable retailer. Cheap and outdated kits might not give accurate results. Always check for an expiration date on the packaging.

Interference

Some medications and medical conditions can interfere with pregnancy test results. Drugs such as tranquilizers, anti-convulsants, and fertility drugs can affect hCG levels in the body, giving a false-negative result.

Do consult your doctor if you are taking any medication that might interfere with the test results.

Human error and Misuse

Human error and misuse can also affect the test results. It’s essential to read and follow the instructions carefully.

Conclusion

In conclusion, pregnancy tests are a valuable tool used by women to confirm pregnancy. With proper usage and care, they offer high levels of accuracy and are readily available over the counter.

Understanding how the tests work, the types of tests available and the factors that can influence their results can help increase the chances of getting reliable results.