1. What is human chorionic gonadotropin (hCG)?
Human chorionic gonadotropin (hCG) is a hormone produced in the women's organism immediately after the embryo implantation in the uterus, which occurs 7-10 days after ovulation (according to statistics - on the 9-10th day). This hormone begins to be produced from the first hours of pregnancy and increases several thousand times until the 7-11th week, then gradually decreases. It is on the qualitative analysis of the presence of hCG in urine that pregnancy tests are based on.
2. What is sensitivity, and what do its values mean?
The sensitivity of a pregnancy test is expressed in mIU/ml (international units per milliliter) and ranges from 10 mIU/ml to 40 mIU/ml. The lower the indicator, the more sensitive the test is and the earlier it can determine pregnancy.
Most tests have a standard sensitivity of 20-25 mIU/ml. The test with such sensitivity gives an objective result no earlier than a week's delay of menstruation. Tests with a sensitivity of 10 mIU/ml can detect pregnancy even with a low level of hCG in the testing sample. That is why they can be used for testing even on the 7th day of pregnancy (1-2 days before the expected menstruation).
3. What are manufacturers guided by when making pregnancy tests?
When making tests, manufacturers proceed from average statistical data that a woman's menstrual cycle is approximately 28 days, and ovulation and conception occur around the 14th day of her monthly cycle. This means that the average woman will theoretically be able to get a correct test result if she takes it about two days before the expected menstruation. However, this is not true for all women, as for some, the menstrual period may be shorter or longer, and ovulation and conception may occur earlier or later. In such cases, it is necessary to take a pregnancy test when there is already a delay in menstruation.
4. On what day after ovulation can the test be performed?
In principle, a positive result can be obtained already on the 7th day after ovulation. Embryo implantation takes 6 to 12 days (usually — ten days). In 90% of cases, by this period (6th-12th day after ovulation), the embryo has already implanted and begins to produce hCG. However, in 10% of pregnancies, the implantation may occur at a different time. If menstruation is delayed by one week, implantation occurs in 97% of cases. That is why all gynecologists advise their patients to take tests only after a delay in menstruation!
5. Why can the test result be wrong?
If the hCG concentration is insufficient, the test result may be false-negative. This can happen when conception is formed just before the start of menstruation, and hCG has not yet accumulated in sufficient quantities for diagnosis.
Detecting the precise moment of ovulation, fertilization, and implantation is almost impossible. Recent scientific studies have shown that in approximately 10% of cases, implantation takes place much later, only after the first day of delayed menstruation, which is why there may be a delay in obtaining a positive result.
6. How does the hCG level increase in a pregnant woman's body?
Consider an example:
We know that the level of hCG increases gradually (every day by two times). Suppose the fertilized egg was attached to the uterus on the 7th day after ovulation. The hCG level rose to 2 mIU that day, 4 mIU on the 8th day, 8 mIU on the 9th, and 16 mIU on the 10th. From this calculation, we can conclude that tests with a sensitivity of 10 mIU will be able to determine the level of hCG in a woman's body on day 10, provided that the pregnancy proceeds in a standard way, without deviations.
Now consider implantation on the 10th day. On the 10th day, the hCG level rose to 2 mIU, on the 11th day — to 4 mIU, on the 12th — to 8 mIU, and on the 13th — to 16 mIU. Thus, if implantation took place on the 10th day after fertilization, then tests with a sensitivity of 10 mIU will be able to determine pregnancy in a woman's body on the 13th day, that is, on the first day when menstruation should begin.
The female body is sometimes unpredictable. In 1% of cases, implantation occurs on the 3rd day after conception, and in 3% — it happens on the 12-13th day after conception. Therefore, gynecologists recommend carrying out pregnancy tests in the first days of the menstrual cycle delay (to avoid a false-negative test result).
Our Company is in solidarity with the opinion of gynecologists, as we care about you, dear women, and do not want to mislead you with unreliable results. We want to take into account the peculiarities of each organism, and therefore we do not take into account the "ideal model" of the pregnancy process.
"Home Test" 10 mIU / ml tests earn a fair well-deserved reputation as a reliable test. We constantly improve our products, providing them with qualitatively excellent characteristics. So, for example, one of them is a change in the packaging, which has become more understandable and readable for the user.
Now, having considered the answers to the above-listed questions, you can understand why we stopped writing on the boxes "from the 7th day after fertilization" and started writing "from the 1st day of the delay". The new inscription is not just the technical information, but our recommendation, because it is on the first day of the delay, that you can get a reliable result, taking into account all the individual characteristics of the female body.
