Pharmacy pregnancy tests are true allies for women when the question of pregnancy arises. They are becoming more effective and sensitive, and some are even as accurate as the blood test beta-hCG itself. Many brands are very reliable, offering up to 99% accuracy in their results1. Most of the pharmacy pregnancy test models available for sale undergo strict quality criteria, and if they show a strong positive, with two well-defined and visible lines, they can give women almost complete certainty of pregnancy.
The biggest challenge is knowing which pregnancy test is trustworthy and when to take it, as testing at the right time also influences effectiveness. You may be wondering: with so many options, brands, and different prices on the market, which one should you choose? First, we need to understand how the test actually works.
- How does the pregnancy test work?
- What types of pregnancy tests are there?
- Which is the best pregnancy test?
- Pharmacy test or blood test?
- How much does a pharmacy pregnancy test cost?
How does the pregnancy test work?
When a woman has a fertilized egg that becomes a zygote (union of egg and sperm) and it is successfully implanted inside the uterus, hCG, the exclusive pregnancy hormone, begins to be secreted.
Beta-hCG is a hormone produced by the trophoblast (structure of the zygote that will give rise to the placenta) as soon as the zygote implants into the uterine wall2. Because it is a hormone that only appears during pregnancy, both pharmacy and laboratory tests look in the sample analyzed (urine or blood) for molecules of this element.
The zygote is the cell formed by the union of the female gamete (egg) and male gamete (sperm). As the pregnancy progresses, the zygote will develop into the embryo, which later develops further to become a fetus.
Pharmacy tests have specific antibodies for beta-hCG in their test area. When urine enters this area of the strip, if beta-hCG is present in the sample, it will bind to the antibodies, provoking a chemical reaction that causes the line to change color, indicating a positive result.
This is the moment when the pharmacy pregnancy test comes into action, as its function is precisely to identify the presence of this hormone in the urine. When hCG is in the urine and blood, it is assumed that the woman is really pregnant3.
It’s important to remember that not every pregnancy test indicates positive with a colored line. That’s why it’s important to read the instructions in the package to ensure you’re interpreting the result correctly.
What types of pregnancy tests are there?
There are two main types of pregnancy tests: blood tests, performed in a laboratory, and urine tests, bought at pharmacies or online stores. Both laboratory and pharmacy tests will look for the beta-hCG hormone in a sample. The main difference between them is that the blood test is much more sensitive to the hormone than the urine test.
Laboratory pregnancy test
The laboratory pregnancy test is nothing more than a blood test where hCG hormone molecules are sought in the woman’s bloodstream. There are two varieties of this test: quantitative or qualitative.
- Quantitative beta-hCG: in addition to looking for hCG in the blood, this type of test also quantifies the concentration of the hormone in the sample. That is, it tells you how much hCG is in the bloodstream and based on this quantity, it is possible not only to determine a positive result, but also estimate how long the woman has been pregnant.
- Qualitative beta-hCG: this is the simplest laboratory pregnancy test. It looks only for the presence of hCG in the blood. The downside of this test is that, depending on the reference value used by the lab, the result may be a false negative or false positive.
False results in laboratory tests are extremely rare, but we cannot say they never occur. To avoid this type of situation, it is always recommended to ask about the reference values for quantitative tests before having the exam.
If you are looking for a precise and detailed result, quantitative beta-hCG is your best option. Famivita allows you to take your beta-hCG test without leaving home. Just go to the Famivita website, select your preferred day and time, and a partner nurse will come to your house to collect the sample.
You receive the result in a few hours, delivered electronically. It’s an excellent option for those wanting more reliable results without having to go out or pay extra for an at-home collection.
Rapid pregnancy test
Rapid pregnancy tests are the most widely used around the world. Not only for their practicality and speed of results, but also because they are easily found. All pharmacy tests work in the same way: when in contact with urine, the antibodies present in the test area of the strip look for beta-hCG molecules.
If these molecules exist, the antibodies specific for beta-hCG will bind to the hormone, promoting a chemical reaction that will cause a change in the indicator in the test area, signaling a positive result.
Besides the various models in color, size, and way of collecting urine, there’s a factor that distinguishes pharmacy tests. Sensitivity to beta-hCG is one of the main factors when deciding which test to buy.
Most tests found in stores have a sensitivity of 25 IU/mL. This sensitivity can only detect pregnancy after a missed period or when pregnancy reaches about four weeks. Even though it’s a reliable option, this type of test tends to have a higher rate of error, such as a false negative.
Which is the best pregnancy test?
The best pregnancy test is the one that can detect even the smallest amount of hCG in a woman’s urine. Most tests already have a sensitivity of 25 mIU, but the most sensitive on the market have a sensitivity of 10 IU/mL, being capable of detecting pregnancy sooner, before a missed period.
These tests, while not error-free, have a much lower rate of false results.
Abroad, there is a digital pregnancy test with 10 mIU sensitivity which is the dream of many women trying to conceive, as it tells for sure if it is positive and even how many weeks the probable pregnancy is.
If we compare all pregnancy diagnosis options, the best pregnancy test is the quantitative beta-hCG blood test, which has the most reliable method. This exam will search a sample of a woman’s blood for beta-hCG molecules and quantify the hormone’s concentration. This information is not only able to determine positive or negative, but also the estimated length of pregnancy. Therefore, this is the most accurate and reliable pregnancy test.
Pharmacy test or blood test?
Which test is more worthwhile, the pharmacy or the blood test? Of course, the blood test! But we must take into account the practicality of the pharmacy test, which can be done at home and without blood collection. Regarding pharmacy pregnancy tests, the most used brands, according to research, are:
Reliable brands
- Famivita (strip)
- Confirme (pen or strip)
- Clear Blue (pen or strip)
- Confira (strip)
- Maxtest (pen or strip)
- Uni test Plus (strip)
How much does a pharmacy pregnancy test cost?
The price difference can be significant. For example, the pharmacy pregnancy test Confirme is much more affordable than Clear Blue Easy. That’s because Clear Blue, according to the manufacturer, has a sensitivity that allows it to detect pregnancy up to 4 days before a missed period.
Confirme is among the most effective tests when taken after a missed period, but is still a good brand when pregnancy is suspected. Clear Blue Easy costs around R$13 to R$30, while Confirme strip costs on average R$10.00 and the pen R$27.00. The Confira strip test, pack of 5, costs around R$19.90 and Confira pen test, 2 units, costs about R$27.90. Famivita’s pregnancy test costs R$5.95 per unit, or in a pack of 10 strips with a discount, each strip is R$3.49. Other brands have a price range around R$16.00, but this can vary depending on your location.
Readers’ Questions
When should I take the test?
Even though there are pharmacy pregnancy tests with such low sensitivities, it’s still best to wait for a missed period before testing. If done before, there may not be enough time for hCG to appear and this can lead to unnecessary disappointment, like a false negative. Pharmacy pregnancy tests are great allies, as long as they’re taken on the correct days. If you are trying to get pregnant or suspect you may be, it’s best to wait at least five days after a missed period to take the test. If it’s still negative, wait another week and repeat the test. Is it still negative? Consult your doctor, as it may be an anovulatory cycle or late ovulation.
How do you use the pen-style pharmacy pregnancy test?
The instructions for using a pen-style pregnancy test are basically the same as for a strip test. The difference in some models may be the way the urine contacts the test. Usually, the pen-style pregnancy test does not need to be put into a cup of urine—you just urinate directly onto the absorbent tip and wait the indicated time to read the result.
Can a pharmacy pregnancy test be wrong?
Yes. Even though manufacturers claim that the test has 99% accuracy, there is still that 1% that can go wrong. Also, the test can be wrong if it’s taken too early or used incorrectly. When in doubt about a result, we recommend taking a second test or a beta-hCG blood test to confirm.
What is a false negative?
This result occurs when the test cannot detect hCG and gives a negative result. This is the most common error in pharmacy tests and the main factors for this are:
Low hCG sensitivity: The test cannot detect hCG in the urine because the pregnancy is still very early and the hormone levels are lower than what the test detects.
Irregular menstrual cycle: Because of an irregular cycle, the woman may take the test too early, before her missed period. In these cases, depending on cycle timing, even more sensitive tests may give false results.
Test error: Like all pharmaceutical products, pharmacy tests have an expiration date. False negatives can happen if the test is used past its expiration date, or if it’s performed incorrectly. For this reason, always check the manufacturer’s instructions and the product’s expiration date before testing.
What is a false positive?
This result occurs when, for some reason, the test detects beta-hCG but what is happening is not a pregnancy. This is the rarest type of false result and usually happens because of one of the following situations:
Chemical pregnancy: This is when the zygote (fertilized egg) begins implantation in the uterine wall, but for some reason, the process is interrupted and a miscarriage occurs. Because it happens at a very early stage, a chemical pregnancy is often mistaken for a late period.
Use of medications: Some medications may contain high amounts of beta-hCG or interfere with metabolism and may alter results. Fertility drugs contain high hCG doses and can influence the test if they were used a few days before testing.
Illness: Besides pregnancy, beta-hCG can also show up when a woman has an illness that affects hormone production. The most common conditions are tumors, such as those found in breast and ovarian cancer cases.
How to avoid pregnancy test errors?
Although rare, pregnancy test errors happen and no one is immune to them. To avoid this kind of situation, there are some measures you can take.
- Use a pregnancy test with a sensitivity of 10 IU/mL;
- Check the product’s expiration date;
- Read and follow the instructions for use;
- Check if any medication you take can interfere with the result;
- Take a blood test (quantitative beta-hCG);
- Repeat the test after a few days.
With these simple tips you reduce the chance of any error related to the test you choose. However, unfortunately they cannot guarantee that the results will be 100% true, since there are other factors that may affect the test.
