The most reliable confirmation of conception can be in the hospital, having donated blood for laboratory testing, but most women want to do it at home. Special tests were invented for self-detection of pregnancy. They are sensitive to the chorionic gonadotropin (a hormone secreted by the future placenta) in the urine.
What are the tests for pregnancy?
The principle of operation for all described devices is identical, but the degree of sensitivity and the correctness of the results are different. The following types of pregnancy tests will be discussed in detail below:
- strip;
- BB;
- jet;
- electronic.
Test strips for pregnancy
This is the most inexpensive, simple and accelerated way to find out whether a conception has occurred. The packaging of such goods contains one or two paper strips impregnated with a special reagent that is sensitive to chorionic gonadotropin ( hCG ). Each rapid test for pregnancy should be immersed in a container with freshly collected urine for several (5-15) seconds. The analysis time is 3-5 minutes. Along with these advantages, the presented devices also have disadvantages:
- The results of a pregnancy test are often mistaken. They are affected by too many extraneous factors - the time of collection of urine, the error in the use of the strip, the violation of production technology at the plant, and more. Sometimes false results appear in response to medication or endocrine imbalance.
- Low sensitivity. The presented version of the device reacts only to a high concentration of the placenta hormone - from 25 mMe. If the described test is done on the 1st day of delay, its reliability does not exceed 85-95%.
- Disadvantages. The woman has to collect only the morning urine in a clean or sterile container.
BB-test for pregnancy
This type of accessories is also available in the form of paper strips impregnated with reagents, but has several distinctive features. This pregnancy test reacts solely to chorionic gonadotropin and is insensitive to other hormones, so it will not show false results against the background of endocrine disorders. BB-strips are more informative, they reveal pregnancy and at low concentrations of hCG - from 10 mMе. You can even use this pregnancy test before the delay, but not earlier than 3 days before the start of the proposed menstruation.
Disadvantages of the device:
- high price in comparison with simple analogues;
- paleness or indistinctness of the resulting strips;
- inconvenience due to the collection of morning urine in sterile dishes.
Tablet tests are still available on the market. They are much more expensive than paper strips, but they are completely identical. The only difference is the presence of a plastic body and a pipette in the kit. In the test there is a similar device with a sensitivity of 10-25 mM, it simply does not need to be immersed in urine. The biological fluid should be dripped into a special window using a pipette and wait for the result. It makes sense to purchase these devices to gracefully inform the partner about conception or to save the tablet for the memory of the exciting moment.
Injection test for pregnancy
Accessories of the third generation are considered as convenient, fast and accurate. The tests described are made from fibrous material with tubules, which quickly absorbs urine. Such devices do not need to be immersed in the biological fluid, the receiving end is just put under the jet. This is the most reliable pregnancy test - after conception it reacts almost immediately, even at a minimum concentration of hCG (about 10 mM), the correctness of the results reaches 99.9%. The only drawback is the high cost of this accessory.
Electronic pregnancy test
The age of the progression of digital technologies has also affected the ways to confirm conception. The most modern pregnancy test is equipped with an electronic chip to read information about the content of chorionic gonadotropin in the urine, and a small display that displays an answer in the form of "+" and "-" signs or "pregnant" and "not pregnant".
The principle of operation and reliability of the considered devices are completely identical to the jet analogs. This is the most informative pregnancy tests - in early terms, they are almost 100% of the cases show the right result. The only difference is in the way it is obtained. On the electronic display the answer is reflected very clearly and unequivocally, the woman has no doubts because of indistinct, pale or bifurcated strips.
Pregnancy test - which is better?
When evaluating the described means, it is important to focus not only on ease of use and cost, but also on the sensitivity and reliability of the results. The best pregnancy test is one that helps determine conception even at the earliest stages of embryo development and less often shows false answers. Below you will find detailed instructions for choosing the devices in question.
What is the sensitivity of pregnancy tests?
After conception in the female body, the structures necessary for normal bearing of the baby begin to form, one of them is the placenta . Her tissues produce a special hormone - chorionic gonadotropin, its amount is constantly increasing. The presence of hCG registers any pregnancy test. The quality and reliability of these devices depends on the reagents applied to the paper strips or fiber.
The higher the concentration of the hormone, the easier it is to determine it in the urine, this does not require sensitive and expensive reagents. In the production of most cheap tests in the form of paper strips, such reagents are used. They provide reliable results only at a high content of hCG (from 25 mMе), therefore can not confirm conception at the earliest dates and often give false answers.
An accurate pregnancy test is characterized by the use of more advanced reagents. Chemical compounds with increased sensitivity to the chorionic gonadotropin provide detection of the hormone at minimum concentrations - from 10 mMe. This helps to reliably determine conception in the first month of fetal development and before the delay of the menstrual cycle.
Rating of pregnancy tests
Manufacturers of the goods in question often produce several types of devices (strips, tablets, inkjet and others). Pregnancy test - marks worthy of attention:
- FrauTest;
- EviTest;
- Clearblue;
- Innotech (BB Test);
- Rest assured;
- Ladies Test;
- Know Now;
- Bona;
- Certainty;
- Answer.
When to do a pregnancy test?
The reliability of the presented devices depends not only on the quality of the reagents, but also on the correctness of their use. The minimum period, when the test will show pregnancy, is 3 days before the anticipated start of the cycle. Such information content is provided by expensive accessories with highly sensitive reagents, but even in these cases a false answer is not excluded.
Through how many after conception will the test show pregnancy?
Chorionic gonadotropin begins to be produced immediately at the moment of conception, but its concentration in the first month is so small that it is difficult to determine and by blood analysis. The most sensitive pregnancy test can detect hCG in urine with an amount of at least 10 mMe. Not all women have this hormone produced in a standard amount, so the early results can not be considered reliable. A positive pregnancy test is accurate if it is carried out a few days after the delay . The optimal period is 8-14 days.
Do I have to do a pregnancy test in the morning?
The time of the described home study depends on the type of device and the reagents that are used in it. The pregnancy test must be done in the morning, if paper strips (including type BB) and tablets are used. These accessories are impregnated with reagents with low sensitivity, and the concentration of gonadotropin falls during the day, reaching the minimum values by the evening.
The use of jet devices avoids such inconveniences. They can be used at any time of day, because the sensitivity of the chemical compounds applied to the fibrous tissue is 10 mM. The digital test (electronic) for pregnancy is similarly authentic. It shows accurate results in the afternoon and in the evening. The main thing is that the urine should be as fresh as possible.
Can a pregnancy test be wrong?
None of these types of devices does not guarantee 100% accuracy, maximum 99-99.9%. Two strips on the pregnancy test may indicate a false positive result. Possible causes:
- presence in the body of malignant tumors or cysts producing hCG;
- previous abortion, abortion or ectopic attachment of the fetal egg ;
- incorrect storage or use of the test;
- taking hormonal drugs, mainly for the treatment of infertility;
- poor-quality accessory (manufacturing errors).
Pregnancy test - weak streak
Uncertainty is a frequent problem, due to which you have to do an analysis repeatedly or go to a clinic for blood testing. A weak strip on the pregnancy test is due to the same reasons as the false positive response. Sometimes this result indicates incorrect storage conditions (high humidity, sun exposure). It is easy to recognize and the delayed pregnancy test - two strips will have a gray or very light shade. This indicates that there is no chemical reaction between the urine and the reagent, its unfitness.
Pregnancy with a negative test
False positive results also occur frequently, even if the analysis is not performed at the earliest possible date. The negative pregnancy test has the following reasons:
- ectopic attachment of the fetus;
- threat of miscarriage ;
- frozen pregnancy;
- too short a period after conception;
- chronic kidney or cardiovascular pathology in a future mother;
- low-quality or spoiled test;
- taking medications that produce a diuretic effect;
- incorrect use of the device;
- treatment with hormonal drugs;
- low production of chorionic gonadotropin for physiological or congenital reasons.