Test to determine the duration of pregnancy. Pregnancy tests: find out the result early

Before the invention of pregnancy tests, humanity resorted to various methods of guessing the onset of the gestational period. Original pregnancy tests were carried out by wetting grain with female urine, mixing urine with wine, changing the characteristics of biological fluid under the influence of various additives, and also injecting it into a certain type of frog. Thus, it was believed that when pregnancy occurs, grains of wheat or barley, watered with urine, germinate faster, which helped not only to diagnose a successful conception, but also to predict the gender of the child. A repetition of a similar test in the 70s of the 20th century showed a 70% effectiveness of the method for determining pregnancy.

A modern pregnancy test makes it possible to determine with a high probability the beginning of a new life without lengthy experiments with various compositions and grains. The variety of rapid diagnostic tests, however, requires knowing when to take a pregnancy test, how to interpret the result, and which tests are best to use.

Despite the modernization of diagnostic methods, the material for testing remains the same as in the Middle Ages. Urine contains human chorionic gonadotropin, the same hormone whose concentration is assessed when diagnosing pregnancy using a blood test.

In venous blood, the hCG hormone begins to be detected 2-3 days after the chorionic villi begin to penetrate the walls of the uterus. Human chorionic gonadotropin reaches a concentration sufficient for most tests in the excreted urine approximately a week after the start of the process of its production in the body.

If there is a concentration of hCG in the urine sufficient for the level of sensitivity of the test, a reaction of the chemical on the surface of the test and the hormone occurs. In the absence of the hormone or its insufficient concentration, the reaction does not occur, and the result is negative.

The average sensitivity of tests on the market is 25 mUI; hCG usually reaches this level two weeks after fertilization. Existing tests with higher sensitivity, reacting to smaller amounts of the hormone, diagnose its appearance 3-4 days earlier.

When can I use the test during a regular menstrual cycle?

If the menstrual cycle is regular and has a constant number of days between the onset of bleeding, then calculating the date of ovulation is easy. The middle of the cycle (with a standard menstrual cycle of 28 days - on the 14th day) the egg is released.
Fertilization of an egg is possible within three days, its life cycle. After the process of fusion of the egg and sperm for 4-5 days, the germ cells migrate through the uterus to the placentation site, after which the production of hCG begins. Assuming fertilization within 2 days, 4 days of migration and the time necessary to achieve the desired level of concentration in the urine of the hormone, highly sensitive tests are able to show the onset of pregnancy 10 days after ovulation, that is, with an average cycle of 28 days - on the 24th day of the cycle . For greater confidence, experts recommend using a highly sensitive test on the 12th day after the release of the egg from the ovary, and tests of ordinary sensitivity - after 15-16 days.

Diagnosis of pregnancy with irregular cycles

If the menstrual cycle is not regular, the duration of the periods between menstruation varies, then the time to use the test depends on the date of ovulation.
Ovulation can be determined by subjective sensations (some women feel characteristic tingling in the area of one of the ovaries, a feeling of fullness, swelling, changes in sensitivity, mood), as well as by measuring rectal temperature and using an ovulation test. To determine the onset of ovulation and possible fertilization, a pregnancy test is used 15 days after the due date.

Morning is wiser than evening: when is the best time to take a test?

Most modern test strips do not limit the diagnostic period to any time of day: they can be used in the morning, afternoon, and night. However, experts, taking into account the possibility of a natural decrease in the concentration of hCG after drinking a large amount of liquid, recommend resorting to diagnosis in the morning, using the first portion of urine after a night's sleep, especially if the probable stage of pregnancy is short.

During the day, when fluid enters the body, the concentration of the hormone decreases. For periods more than 18 days after ovulation, this factor is not decisive, but the timing of ovulation also does not always coincide with the expected one. For accurate indicators, it is better to follow the recommendations of specialists, and in a situation where the test needs to be carried out during the day or evening, the optimal diagnosis would be after four hours of abstaining from going to the toilet and limiting the consumption of liquid products to maintain the level of hCG concentration.

Rules for using rapid tests

It is necessary to follow the test storage rules provided by the manufacturer.
Using the test in damaged packaging may distort diagnostic results.
The package is opened immediately before diagnostics.
Using an expired test will result in incorrect results.
The optimal time for the test is in the morning, immediately after a night's sleep.
If the test is not a jet test, urine collection requires the use of a clean container.
It is recommended to carry out hygienic procedures including washing the external genitalia before testing.
Strictly follow the instructions for use.

Pregnancy test: instructions for use

There are different types of rapid tests. Instructions for each type are attached to the test; violation of the rules of use most often results in the appearance of incorrect indicators.

When diagnosing pregnancy, the test is used within the time frame specified by the manufacturer. If testing is recommended from the first days of the delay, then there is a possibility that the sensitivity of the reagent or individual characteristics, the timing of conception will allow pregnancy to be detected earlier than the specified period, but most often an accurate result is possible only on the indicated days of the cycle.

The cost of the test most often directly correlates with its reliability: the lower the price, the lower the production cost and the cheaper the chemical reagent, respectively, the higher the number of incorrect results. The most common tests on the market today are four modifications; each type has its own characteristics and instructions for use. Some manufacturers produce different types of tests under a single brand (Evitest or Evitest, Frautest, etc.); when purchasing, you need to pay attention to the variety.

Test strip or strip test

The strip test is one of the first options for diagnosing pregnancy, a test for independent use and quick interpretation of the results. The most common and cheapest option (for example, Itest Plus is offered at a price of 20 rubles).
A paper-plastic strip with an additional inner layer impregnated with reagents becomes colored in one or two places upon contact with urine. One strip confirms the effectiveness of the test, two indicate the presence of a sufficient concentration of the hormone human chorionic gonadotropin to confirm pregnancy.

Directions for use: collect the first morning urine in a clean container, lower the test to the limit indicated on the strip, hold it in the liquid for the required time (usually 20-30 seconds), remove it and place it on a dry horizontal surface.

Diagnostic results appear within a period of 1 to 10 minutes, depending on the concentration of the hormone. Some tests can also change the degree of color of the control strip - the paler the color, the shorter the gestational age.

Tablet type tests

Tablet tests are based on the same operating principle as strip tests: when a certain part of the surface comes into contact with urine, a chemical reaction occurs between the reagent and the hCG hormone. To reduce the likelihood of error, the volume of liquid is dosed, and the contact point is limited by a special window.
According to the instructions, you need to collect urine in the included clean container, then use the pipette included in the kit to dose 4 drops into the small window of the test tablet. The results are evaluated in the following window: depending on the variety, one or two stripes or a minus and a plus appear.

Inkjet tests

This variety is considered one of the most accurate and sensitive, and also does not require additional devices or manipulations. The test strip is placed under stream of urine for 10 seconds (if necessary, you can use a container and immerse the test in the urine).
Results are to be assessed at intervals of 1 to 10 minutes, depending on the concentration of the hormone. Unlike the above options, jet tests can be used 5 days before the expected date of menstruation.

Digital pregnancy test

Electronic modification of conventional options. The test evaluates the concentration of the hCG hormone and requires immersion in urine, but the result (depending on the type of test) is displayed either on an electronic mini-display or appears on the computer screen to which the test is connected via a USB port.
This option is considered the most optimal due to the impossibility of distorting the interpretation of the results. However, the sensitivity of digital tests is the same as that of inkjet tests: they can be used 3-4 days before the expected date of menstruation. When tested 2 days before the start of menstruation, 99% accuracy is guaranteed.

Negative test result in developing pregnancy

In most cases, tests show a negative result in pregnant women if tests with low sensitivity are used too early, or instructions for use or storage are not followed. A negative result is also possible due to late ovulation and late conception - in such cases, hormonal levels change more slowly than expected in accordance with the menstrual cycle.

Diseases of the endocrine system and hormonal imbalances also lead to negative test results. The threat of miscarriage is characterized by an increase in the level of the hCG hormone that is inappropriate for the gestational age, which, accordingly, leads to one line on the test at a time when the hCG concentration should be sufficient for two.

It is worth knowing that during pregnancy, tests can only be used in the first trimester. The concentration of hCG is not maintained during the period of waiting for the child, which leads to incidents: if tests are carried out for a period of more than 2-3 months, the result will be negative.

False Positives

Positive test results in non-pregnant women are much less common than the opposite situation and in most cases indicate the presence of diseases (ovarian dysfunction, the formation of a tumor in the reproductive organs that produces hormones, etc.). False-positive diagnostic results are also observed in the first two months of the postpartum period and when using an expired test.

Testing during menstruation

In some women, pregnancy is accompanied by menstrual-like discharge, similar in abundance, timing and symptoms to normal menstruation. As a rule, the discharge ends in the first trimester, but there are known cases of its manifestations throughout the entire gestation period. In such situations, it is recommended to resort to diagnosis using a blood test, but the use of tests is also possible.
Any test is based on assessing the concentration of the hormone in the urine and the presence of menstrual fluid in it does not affect the effectiveness of the tests.

If the test results are in doubt

Sometimes it is not easy to interpret the results of express diagnostics: the second indicator strip is slightly marked, visible from the inside of the test. Sometimes this happens due to poor quality production of cheap paper test strips: when wet, the reagent becomes slightly more noticeable than when dry.
A visible but pale second line most often indicates a low level of hCG, insufficient for the sensitivity of the test. In this case, it is better to postpone the check for 1-2 days or use a more highly sensitive option.

A strip with an insufficient degree of color may also appear as a result of improper storage of the test or violation of the instructions. In any case, repeat testing and/or blood testing for hCG is recommended.

Ectopic or non-developing pregnancy

The test results for an ectopic and/or non-developing pregnancy are also positive: on the days of expected menstruation, the presence of a second line on the test is most often noted. But the hormone level does not increase in such conditions; upon repeated testing, the pregnancy indicator strip may turn pale or not appear, which requires immediate consultation with a doctor.

Confirmation of pregnancy is an important moment. The sooner a woman learns about her new condition, the faster she will change her lifestyle. Carrying a baby imposes certain restrictions on physical activity, working conditions, and treatment of diseases.

Pregnancy confirmation

The easiest way to confirm pregnancy is to go to the pharmacy for a special test. They come from different manufacturers, different designs and different prices.

However, any pharmacy test is based on one principle - the interaction of an indicator in a certain zone with a hormone contained in the urine of a pregnant woman.

We are talking about human chorionic gonadotropin (hCG). It is the most reliable confirmation of successful conception, since it is produced in the body only during the period of bearing a child. There are certain diseases in which it appears in the blood, but they are extremely rare.

From the moment the fertilized egg is implanted, hCG is actively produced by the woman’s body, and its level in the blood increases rapidly. In two days the content of this hormone doubles. Human chorionic gonadotropin is excreted in the urine and this is what the action of indicator tests is based on.

Of course, its level in the blood is higher, and pregnancy can be confirmed earlier. But this method is not routine. Examining urine is much easier, cheaper and painless. However, the question remains of how accurate and informative pregnancy tests are.

Accuracy

Even the cheapest pregnancy tests are quite accurate. If they were stored under appropriate conditions and the expiration date has not expired, then you can buy any indicator and safely use it.

Since during the test a chemical reaction occurs between human chorionic gonadotropin and the indicator substance, there are practically no false positive reactions.

This means that you cannot see two stripes in the absence of pregnancy; the indicator is specific enough not to react to other hormones. But with sensitivity the situation is somewhat different.

Sensitivity

The sensitivity of a pharmaceutical indicator is its ability to detect a minimal amount of human chorionic gonadotropin and demonstrate this as a positive result. The lower the hormone content, the more accurate the test.

But sensitivity depends not only on the indicator. It is also influenced by the conditions of the event. For example, the concentration of human chorionic gonadotropin will be higher in the first morning urine, since it has accumulated there throughout the night. And in this case, even a low-sensitivity device is able to react to increased levels of the hormone.

Based on this parameter, there are three types of tests:

Low sensitivity.
Medium sensitive.
Highly sensitive.

Low sensitivity

These devices are usually the simplest and cheapest. They are a paper strip, one end of which is impregnated with an indicator substance, and the other has a control strip. When a similar strip appears nearby, the result is considered positive.

Low-sensitivity tests can respond to hormone concentrations in the expectant mother’s urine of 25–30 mME/ml or higher. This means that in the first days after the delay, their accuracy will be low, and the percentage of false negative results will be quite high. And, of course, you should not use them before the expected start of menstruation.

How many days must pass after the delay before the test shows a reliable result? It is better to wait at least three to five days, otherwise the analysis will most likely have to be repeated again.

Low sensitivity includes:

Test for best.
Mon ami comfort.
Clearblue.

Medium sensitive

This is the most common group of indicators. Their cost is average. The accuracy is quite high. They respond to human chorionic gonadotropin levels of 20 mIU/ml or higher.

This means that the very next day after your missed period you can use tests from this group.

Of course, when using them there is also a possibility of obtaining a negative result, but this happens much less often. As a rule, unreliable results are a consequence of improper use of the device.

Medium-sensitive tests are produced not only in the form of paper strips. There are more expensive and convenient models - cassette and tablet indicators. They allow you to confirm pregnancy at any time and in any conditions – for example, at work.

Moderately sensitive tests include the following:

Frautest.
Evitest and Evitest plus (the package contains two indicators in case of a false negative result).
HCG biocard.
Mama test.

Highly sensitive

From the name it is clear that these devices respond to the minimum possible concentration of the pregnancy hormone, which is 10–15 mME/ml. The cost of these tests is usually quite high, but they justify it with their accuracy.

How many days before the expected delay of menstruation is it recommended to use a highly sensitive indicator? The manufacturer says 5–7 days, but in practice it is still better to determine pregnancy on the eve of the expected period. A few days will not change the situation, but the accuracy of the analysis will increase, which will help avoid additional expenses when purchasing another test.

Highly sensitive tests are produced in the form of strip strips, cassettes, tablets and electronic devices. There is no need to collect morning urine for them, because they are able to detect the minimum concentration of hCG in any portion.

The following are considered highly sensitive:

Ultra test with 99.9% accuracy.
Sezam (cassette test).

Sometimes indicators that respond to a concentration of pregnancy hubbub of 10 mME/ml are called ultrasensitive. And their accuracy is close to 100%.

But even when using the most low-sensitivity tests, you can get a highly accurate result if you follow all the rules specified in the instructions.

Proper Use

Before you begin the analysis, you must carefully read the instructions. In most cases, the accuracy of the result depends on this.

If a low-sensitivity indicator is used, there is no need to try to get ahead of events and start checking before the expected delay. No matter how strong the confidence in successful conception, during this period the result is most likely to be false negative.

Also, you should not carry out the analysis in the evening if the manufacturer clearly indicates in the instructions the morning time for its use. This will increase both the sensitivity and accuracy of the device.

It is important to correctly evaluate the result. In how many minutes will it be reliable? You can usually search for two lines or the word “pregnant” within 3-5 minutes. Each manufacturer separately stipulates this point in the instructions. But if after this time the result remains negative, then it will not change in the future. Regardless of how many stripes or what signs appear on the indicator after 20–30 minutes or 3–5 hours, it is already considered uninformative.

Do not touch the indicator zone with your hands to avoid contaminating it. And of course, we should not forget that the accuracy of the device directly depends on the concentration of human chorionic gonadotropin. This means that even highly sensitive tests will show a false negative result if you drink a lot of liquid or go to the toilet before the test.

If the desired second line does not appear even after a delay, do not despair. You just need to repeat the analysis.

Reanalysis

Repeated analysis is carried out after 3-5 days if the delay continues. The more time passes, the more reliable the result. Some women use the same indicator for these purposes. But it is better to use a test from another manufacturer.

In addition, you need to pay attention to the sensitivity of the device. If the first attempt was carried out with a low-sensitivity indicator, the second time it is better to purchase a more expensive and accurate option.

But if all tests within 7-10 days after the delay are negative, and menstruation still does not begin, you need to consult a gynecologist about menstrual irregularities.

The accuracy of a pregnancy test depends on many factors. Before performing an analysis, it is important to select a highly sensitive indicator and use it in accordance with the instructions.

So, you saw the coveted two stripes on the test, but doubts creep into your head - what if there was an error? We've collected answers to the 10 most common questions about pregnancy tests.

1. How does a pregnancy test work?

All pregnancy tests operate on the same principle - they recognize a special hormone called human chorionic gonadotropin (hCG) in urine (tests for home use) or blood (laboratory tests). It is produced only during pregnancy. A non-pregnant woman simply cannot have it. The level of hCG in the body from the moment the fertilized egg attaches to the wall of the uterus doubles approximately every 2-3 days and reaches a maximum at 7-12 weeks of pregnancy. Its presence in the blood and urine persists until approximately the third week after the birth of the child.

2. Can a pregnancy test be taken during the day? What time of day is best to do it?

Usually, morning urine is used to perform a pregnancy test, as it is more concentrated. But there is a test that can be done both during the day and in the evening - the exact time does not matter. This is a jet test. They are especially sensitive (look for the 10 mIU/ml mark on the package), and when using them, there is no need to collect urine anywhere - just put the test under the stream.

3. Are pregnancy tests wrong?

All instructions say that pregnancy tests are 95–99% accurate. This means that there is a chance that the result will be incorrect. So, false negative the result (the test does not show pregnancy, although there is one) is possible if:
you performed the test too early and the level of hCG in the urine is still too low;
the test has expired (read the packaging carefully before buying the test);
you performed the test incorrectly (read the instructions carefully, everything is extremely simple there);
Drinking too much liquid the day before the test can dilute the urine and reduce the concentration of hCG.

The test can also show false positive result (there is no pregnancy, but the test says that there is).
This happens if you are taking fertility drugs that contain hCG (usually in the form of injections);
In the presence of malignant tumors;
A positive pregnancy test result may also mean that remnants of the fertilized egg remain in the uterus after premature birth or miscarriage.

4. On what day of delay should I test? Does it make sense to take a pregnancy test before your delay?

The sensitivity of pregnancy tests plays a big role. In general, most tests have a sensitivity of 20–25 mIU/mL (international units per mL). They are able to recognize pregnancy only from the first day of missed menstruation. Whereas there are more sensitive (10 mIU/ml), but also more expensive tests that determine pregnancy before the delay - already 7-10 days from the moment of expected conception. And after a week of delay, any tests will show pregnancy (if there is one). The level of hCG in the blood grows faster than in the urine, so pregnancy can be determined even before the expected menstruation (but not earlier than 7 days from the date of expected conception) - using a blood test for hCG, which can be done in a antenatal clinic or in commercial laboratories.

5. How to use a pregnancy test correctly?

There are different types of pregnancy tests, and they must be used in accordance with the instructions for each of them. For example:

Strip tests (test strips)
These are the simplest, cheapest and most common tests. The strip needs to be lowered for 10–20 seconds to a certain mark in a container with morning urine (it is the most concentrated). After this, the test should be placed on a horizontal surface and after a few minutes the result can be assessed. One line means you are not pregnant, the test showed two lines - pregnancy has occurred.

Tablet tests
They are designed in the same way as strip tests. Only the paper strip is placed in a plastic case. And the previously collected morning urine needs to be dropped into a special hole with the pipette included with the test. One or two stripes on the test will also tell you about the result.

Inkjet tests
Their convenience is that there is no need to collect urine anywhere - just place the test under the stream. In this case, urine does not have to be morning. Inkjet pregnancy tests are usually more sensitive. Again, a positive test result means two lines, and if only one line appears, then the test shows a negative result.

Electronic tests
These tests have a special strip - a sample receiver, which can optionally be lowered into a container with urine or placed under the stream. The result is read in 3 minutes. If “+” or the inscription “pregnant” appears on the test, you are pregnant, but if “–” or “not pregnant”, you are not.

6. Why is there a weak second stripe?

Even if the test shows a weak second line, this still means that you are pregnant, it’s just that the level of hCG in your blood is not that high yet. If in doubt, retest in 3-4 days. The hCG level will become much higher, and then the strip will be much brighter.

7. The best pregnancy test - what is it?

The answer to this question may vary depending on what you need. If you want to find out as early as possible whether you are pregnant, it is best to donate blood in a laboratory (no earlier than 7 days after the expected conception). If convenience is important to you, then some people prefer jet tests, which can be used during the day and for which you do not need to collect urine anywhere. For some, on the contrary, putting the test under the stream seems labor-intensive, and it is easier for them to collect the urine in a special jar, and then put the cheapest paper test (strip test) in there.

8. Online pregnancy test - what is it?

At best, it's just a hoax. At worst, it’s a way for scammers to make money (when, for example, to pass a test you first need to send an SMS to a specific number). There are different types of tests. Some suggest placing your finger on the blue square on the screen, and if within a few minutes it turns red, you are pregnant. However, even if you don’t put your finger on the screen, the square will turn red on its own after a while. Other tests ask you to answer a series of questions before making a verdict. For example, “Have you had unprotected sex recently?” and “Do you feel engorgement in your breasts?”

9. Does the test indicate an ectopic pregnancy?

If the fertilized egg has implanted outside the uterus, a regular pregnancy test will still be positive. True, if you do not intervene in time, the ectopic pregnancy will terminate on its own at 7-8 weeks, and all this will be accompanied by significant blood loss, pain and serious problems for the woman’s health. To avoid this, it is better to detect early signs of an ectopic pregnancy in advance and terminate such a pregnancy in a hospital. An ectopic pregnancy may be indicated, in particular, by nagging pain in the lower abdomen and spotting against the background of a positive pregnancy test. If you notice these symptoms, immediately go to the gynecologist. It will carry out, and if the pregnancy is ectopic, then there will be no fertilized egg in the uterus, but there will be epithelial growth, as in a normal pregnancy. If you belong to a risk group (adhesions, inflammation of the appendages, or have had an ectopic pregnancy before), it is better to do a qualitative blood test over time. During an ectopic pregnancy, the level of hCG in the blood is lower than during a normal pregnancy, and the test will immediately show this.

10. What stage of pregnancy does the test show? Will the test show the week of pregnancy?

Neither a strip test, nor a tablet, nor an inkjet, nor an electronic test will tell you your gestational age. They are exclusively qualitative in nature - “yes” or “no”. But you can still find out the approximate gestational age. If you do a quantitative blood test in the laboratory. He will determine the exact level of hCG in the blood, after which the doctor will be able to tell which week of pregnancy it corresponds to. Doing such a test is, in particular, useful to recognize a frozen pregnancy in the early stages. If the embryo freezes in development, the hCG level stops growing, which will be seen in this analysis.

Aglaya Jaermund

Surely, all women know about such a simple and accessible way to diagnose pregnancy as an express test. The test helps determine the presence of pregnancy in the early stages. If you receive a positive result, do not delay visiting your doctor to rule out an ectopic pregnancy or any other disease in which the level of hCG (the hormone that the test responds to) increases.

On what principle does the test work to determine pregnancy in the early stages?

To prevent a secondary pregnancy from developing in the body, from the moment of conception a special hormone (hCG) blocks the production of an egg. It is this hormone that tests for early diagnosis of pregnancy react to. The longer the pregnancy, the higher the level of the hormone, respectively.

What types of tests exist for early pregnancy detection?

The most common and popular currently are inkjet tests, which, thanks to special particles inside, react to the presence or absence of hCG. These tests are quite reliable, the probability of their reliability is 90-100%. The jet test allows you to quickly determine pregnancy in the early stages.

The test may show an incorrect result if:

its expiration date has expired;
the woman has diseases that provoke the production of hCG;
were taking oral contraceptives or diuretics.

In addition to inkjet tests, test strips are also very popular (they are easy to use and inexpensive). The test tablet has a special container for collecting urine, which greatly facilitates the procedure. And, of course, electronic tests to determine pregnancy in the early stages. They work on the same principle as the others, only the answer will be either “pregnant” or “not pregnant”.

When is the best time to take the test?

The best time to independently diagnose the presence of pregnancy in the early stages is the morning; in the morning hours the amount of the hormone in the urine is maximum, which allows you to accurately determine the presence or absence of pregnancy. As for the date of the test, it should be done no earlier than the first day after the delay, although many test manufacturers claim that their products can determine pregnancy even before the delay of menstruation. Remember that the amount of the hormone in the urine during pregnancy almost doubles every day.

How accurate are early pregnancy tests?

Early pregnancy tests are quite reliable and accurate. The probability of getting the correct result is more than 95%. But this is only if the test was carried out correctly.

That is why, before you begin diagnosing pregnancy, you must carefully study the instructions for using the test. may be caused by some diseases, and a false negative may be due to too early diagnosis.