There are many reasons why a woman wants to find out about pregnancy as soon as possible or to make sure that she is not pregnant. In some cases, she plans to get pregnant in the near future. In others, she wants to be sure that the contraceptives she uses are working well. Thirdly, the woman is treated with drugs or methods, the use of which during pregnancy is extremely undesirable. Fourthly... The list goes on.
Regardless of the reason, women are looking for an accurate and effective way to detect pregnancy as early as possible. Is there a test that can detect pregnancy before the expected period, and how reliable is its result?
When does egg implantation occur?
Fertilization is a complex process that takes place at the cellular level. For a woman, it proceeds completely unnoticed.
Initial signs of pregnancy (even before the delay) can appear after the egg reaches the uterus after fertilization and attaches to it.
Usually the uterus is attached one week after conception. The fertilized egg merges with the wall of the uterus (its upper part) on days 21-23 of the menstrual cycle.
A fertilized egg already consists of several cells that join together into a single whole. They divide and form a whole cell cluster. As the cells increase in size, the size of the egg also increases.
As a result, one of them will become an embryo, and the rest will be used to nourish and protect it throughout the pregnancy.
Is it possible to determine pregnancy using a test before the delay?
Most women have the opportunity to find out about their pregnancy before their missed period. In each cycle there is a time period suitable for fertilization of the egg, which lasts several days. It is called the fertile window. If conception occurred at the beginning of this period, then there is a high probability that the woman will be able to find out about her pregnancy even before the delay.
The accuracy of the indicators directly depends on the following factors:
- degree of sensitivity of the test,
- the length of the woman's cycle,
- the number of days remaining until the expected date of menstruation,
- time of day at which urine was collected for analysis.
Changes in hCG levels by week of pregnancy
HCG is human chorionic gonadotropin (hormone). Immediately after the transfer of a fertilized egg to the uterine wall, it is formed in the body of the expectant mother. The body needs the hormone until the placenta forms. In the initial stages, it stimulates the production of other important hormones.
Determining the level of hCG is one of the most detailed tests in the twelfth week. For this purpose, urine tests are performed. A pregnancy test may be used.
Hormonal levels change as pregnancy progresses. Until the 12th week it grows (doubling every 48 hours), and then there is a sharp decrease.
The information is reflected in the table below.
| Gestational age | HCG level |
| 0 — 1 | 5 — 25 |
| 1 — 2 | 25 — 156 |
| 2 — 3 | 101 — 4870 |
| 3 — 4 | 1110 — 31500 |
| 4 — 5 | 2560 — 82300 |
| 5 — 6 | 23100 — 151000 |
| 6 — 7 | 27300 — 233000 |
| 7 — 11 | 20900 — 291000 |
| 11 — 15 | 6140 — 103000 |
Tests with varying degrees of sensitivity
Pregnancy tests differ not only in their functionality, price and appearance.
The main criterion for choosing all pregnancy tests is sensitivity.
It is this indicator that determines on what day after ovulation a test should be taken to confirm pregnancy
- Tests with standard sensitivity from 25 mIU/ml.
The higher the number characterizing the test, the less sensitivity it has.
These include test strips and cassette tests. As well as digital tests that show the gestational age, in particular the famous Clearblue Digital test.
- Tests with an average sensitivity of 15 to 25 mIU/ml, such as Fraytest.
- Ultrasensitive tests with readings from 10 to 15 mIU/ml.
An example is the Insure test that recently appeared on the pharmaceutical market (sensitivity 12.5 mIU/ml) or the “Ambulance” test (sensitivity 10 mIU/ml).
Sensitive tests can show pregnancy 5-7 days before the missed period.
A paper strip test is the most inexpensive option for detecting pregnancy. They are impregnated with a substance that reacts to changes in the hCG hormone.
The operating principle of test strips is extremely simple. The strip is immersed in a container of urine for a few seconds. Then you need to wait 5-7 minutes and you can see the result.
When two red stripes appear, there is a high probability of pregnancy. After such testing, it will not hurt to use more modern means or undergo an ultrasound.
If the reagent is unevenly distributed over the surface of the strip, an incorrect result may be shown.
Cassette or tablet tests are also standard. They do not need to be immersed in a container of reagent. Such tests are cases with paper strips enclosed in them.
A small amount of reagent is enough per strip using a pipette, and the result can be seen in a special window in 3-4 minutes. The urine comes into contact with the reagent already present in the test.
Inkjet tests with high sensitivity contain special reagents, which, when detecting human chorionic gonadotropin in female urine, can show a reliable result within a minute.
No containers or pipettes are required to apply urine. This is an accurate and convenient option for detecting pregnancy.
As for digital tests, they are expensive, but they provide the same amount of information.
Unless the period is additionally calculated in weeks. Electronic tests are equipped with special intelligent sensors. If the result is positive, a “+” sign and the gestational age in weeks will appear in the window.
How to use pregnancy tests
Pregnancy tests are easy to use. It is important to follow the instructions to get the most accurate result.
In general, one of the following methods is used:
Urinate directly onto the test strip;
The urine is collected in a cup and a test strip is immersed there.
Many manufacturers recommend using two home tests to confirm results. This happens because hCG levels may be too low to be detected. To ensure accurate results, it is best to wait a few days between two tests.
Many pregnancy test manufacturers claim that the tests are up to 99% accurate. Clinical tests may be more accurate.
When can you take the test?
After the egg meets the sperm in the fallopian tube and conception occurs, active cell division in the fertilized egg begins, and the zygote itself moves towards the uterus.
The fertilized egg descends into the uterine cavity only on the 6-7th day. The embryo can remain suspended for another 2 days, and then deepens into the endometrium.
From this moment, the level of hCG in the woman’s body begins to increase.
Considering that human chorionic gonadotropin doubles every 2 days, the most sensitive test will show pregnancy 10-12 days after ovulation.
Standard tests (sensitivity 25 mIU/ml) show pregnancy only from the first day of delay. But even in this case, the test may show a negative result in case of menstrual irregularities or late ovulation.
Regardless of sensitivity, the test will show an accurate result only on the 3-4th day of the menstrual cycle delay.
All test results before the delay are considered relative. Although if the result is positive, the chances are high that the long-awaited pregnancy has occurred.
Features of the menstrual cycle and the dependence of the time of conception on its duration
One of the main individual characteristics that influences the test results when used before a delay is the duration of the menstrual cycle in a particular woman. Cyclic changes can normally last from 21 to 35 days.
When making calculations, we must remember that the contact of the sperm with the egg released from the ovary does not always coincide with the date of sexual intercourse; fertilization can occur 1–2 days later. This means that the time of conception may shift by this time period, which will affect the level of hCG and the result of the pregnancy test.
Normal 28 day cycle
Most standard pregnancy tests recognize hCG concentrations of 25 mIU/ml or higher. Under favorable conditions, this concentration is achieved on the day that coincides with the expected date of the next menstruation. Therefore, the likelihood of a negative result from such testing is high. For early diagnosis of pregnancy, highly sensitive tests that respond to a hCG concentration of 10–15 mIU/ml are more suitable. With their help, you can determine the presence of pregnancy before the expected date of your next period.
Short cycle
Some women have a shortened cycle, the duration of which is 21 days. Shortening can occur due to the first, second or both phases. With a 21-day period, ovulation occurs on days 8–10. The concentration of hCG, which can be used to detect pregnancy using tests, in such women is reached by the time the menstrual cycle has come to an end, or even later. For these reasons, diagnosing pregnancy before the onset of menstruation is difficult.
In this case, tests with normal sensitivity are not suitable; you need to choose the most highly sensitive varieties. Before a missed period, it is recommended to use digital tests “Evitest”, “Frautest” or “Clearblue”, which are sensitive to lower concentrations of hCG and are more likely to indicate the presence of pregnancy. The domestic version of such tests, Clever, has the same accuracy, but costs much less.
Long cycle
An extended cycle lasting 35 days has its own characteristics. Usually, the first part of the period, before ovulation, is extended, and the second lasts as long as in women with a cycle of 28 days. If you need to test without waiting for menstruation, it is also preferable to use tests that are sensitive to low concentrations of hCG, since conventional ones can give a negative result.
Does the test always show an existing pregnancy?
Often, when you independently determine pregnancy using a test, the result may turn out to be false positive, that is, it will not be confirmed during another study. The test will show two lines if the child is not conceived.
An unreliable result may be a consequence of taking special medications with a high content of the hCG hormone or the presence of trophoblastic neoplasms.
The results may also be false positive after a recent ectopic pregnancy, spontaneous miscarriage or abortion. In this case, even during menstruation, the test may show pregnancy.
The fact is that during this period of time the body still retains an increased content of chronic gonadotropin. Therefore, the results will be false.
You can specify the data and highlight the main reasons for a false positive result:
- use of hCG products. For example, Pregnil, Profasi and others.
- presence of tumors;
- minor elimination of soft tissue after early abortion.
Can a test show pregnancy before menstruation?
As a rule, the very first sign of pregnancy is a delay in menstruation. Many girls do not want to wait for the cherished moment and rush to take a pregnancy test a week before their period. Observation of the fusion of sperm and egg is, by definition, impossible. However, computer reconstruction allows us to understand what specifically affects the performance of tests.
The reagent applied to thick paper can recognize the fetal hormone hCG. If there is not enough of it in a woman’s urine, then the diagnosis will not give results.
Pregnancy occurs during ovulation, which occurs approximately on the 14th day of the monthly cycle. Conception itself does not happen immediately after intercourse - it takes about a week for the egg to penetrate the uterine wall, and about 3 more days for hCG to rise to a sufficiently high level.
Many people are concerned about the question of how many days before menstruation the test will show pregnancy. There is no point in doing it earlier than 4 days before menstruation. However, no one forbids experimenting and checking the results. If the cycle is not regular or longer than usual, then ovulation occurs later. Tests will be effective 14 days after sexual intercourse. That is, with a cycle of 30-36 days, 5 days before your period, the test will show pregnancy.
A week before your period, a test can show pregnancy, or rather two coveted stripes. They cannot always be regarded as a positive sign; sometimes the test reacts to medications taken by a woman or a disease. Sometimes hCG is found in the body of a woman who is not expecting a child. This happens when:
- a woman takes a medicine containing this hormone;
- recently had an abortion;
- I had a miscarriage some time ago;
- ectopic pregnancy;
- incorrect execution of test instructions.
To confirm your expectations, you can measure your basal temperature in the morning. If it is close to 37 degrees, then conception can be considered successful. If the test shows a second unclear line, it is advisable to repeat the test after one or two days.
