When the egg is fertilized and attached, a special hormone, hCG, begins to be produced. By the presence of human chorionic gonadotropin in the urine or blood of a woman, you can find out about pregnancy.
General hormone information
HCG in the body of a woman begins to be produced from the moment of conception, but at first its concentration is so low that it will not be possible to detect it. At the time of fertilization of the egg, a membrane begins to form. It is her cells that can produce this hormone.
You can identify it by conducting a laboratory blood test. You can also learn about egg fertilization and embryo attachment using a routine home pregnancy test. A blood test allows you to not only diagnose pregnancy, but also to determine whether it is proceeding normally. But for this it is necessary to know what results of hCG for what period should be.
Assign this analysis for the purpose of early diagnosis of pregnancy. Indeed, compared to conventional home tests, this method is considered more informative. Also, this study will help determine the status of placental function. It allows you to identify violations in the uterus-fetus system.
Interpretation of analyzes
In the blood, chorionic gonadotropin can be detected within 7-10 days after fertilization has taken place. When pregnancy occurs at this time, the concentration of this hormone exceeds the established negative norms of 0-5 units.
But it is better to donate blood after a delay. After all, the concentration of hCG begins to increase markedly only after implantation. In most women, this occurs on the 7th day after fertilization. But there are cases when a fetal egg is implanted in the uterine wall 2-3 days later. If at this time you pass an analysis for hCG, then it will be negative.
Therefore, gynecologists advise to wait for the estimated date of menstruation and only after that go to the laboratory. So you can get the most reliable results.
If the expected date of the monthly hCG is negative, but critical days do not occur, then you can retake the analysis after 3-5 days. Ovulation may have delayed and the egg will be fertilized a few days later than the expected date.
The results of hCG allow you to find out the gestational age. If you take this analysis in dynamics with a certain frequency, then you can understand whether the baby is developing normally in the womb. This is determined by the growth dynamics of the concentration of this hormone. Normally, he should double every 2-3 days. But it makes sense to monitor it only until 9 weeks, after this period its concentration may begin to decline.
Pregnancy definition
Having donated blood for analysis, women often cannot wait for the result. HCG is negative if its concentration is in the range of 0-5 units. Indicators above 25 units indicate pregnancy.
But it happens that a woman receives an answer, which indicates that the concentration of hCG varies between 5 and 25 units. This is the so-called gray zone. According to such an analysis, it is impossible to say that pregnancy has come. After all, such indicators may indicate that fertilization has occurred recently, and the amount of the hormone has not yet managed to increase to the required level.
In addition, such hCG results may indicate that the egg is fertilized, but could not attach to the uterine wall. In this case, it is necessary to wait for menstruation. If it does not start, it makes sense to retake this analysis. It is important to look at the dynamics of indicators. After all, such a result may indicate an ectopic implantation of the ovum.
If the hCG hormone is present in an amount of more than 25 units, then the egg is most likely already attached. For a period of up to 2 weeks, counting from the date of conception, the level of chorionic gonadotropin should be in the range of 25-156 mU / ml. Its concentration increases quite quickly.
To check whether the gestational age corresponds to the test results, the hCG table will help.
Estimated period from conception / last period | The concentration of the hormone, honey / ml |
1-2 / 3-4 | 25-156 |
2-3 / 4-5 | 100-4 870 |
3-4 / 5-6 | 1 111-31 500 |
4-5 / 6-7 | 2 500-82 400 |
5-6 / 7-8 | 23,000-151,000 |
6-7 / 8-9 | 27 300-230 000 |
7-11 / 9-13 | 21 000-291 000 |
11-16 / 13-18 | 6 100-103 000 |
16-21 / 18-23 | 4 720-80 000 |
21-39 / 23-41 | 2 700-78 100 |
If the period set in the laboratory on the basis of the test results does not coincide with the one that you have, then you should additionally consult with a gynecologist and go for an ultrasound scan.
Possible causes of increased hormone levels
In some cases, women get results that do not match their expected gestational age. The concentration of the hormone can be either more than the established norm, or less than it.
If you get a hCG test result in which the level of chorionic gonadotropin is higher than it should be, then this may indicate:
- multiple pregnancy;
- the development of diabetes in the expectant mother;
- incorrectly established gestational age;
- possible developmental pathologies, for example, about Down syndrome or multiple defects.
In addition, an increased level of hCG can be with the development of toxicosis in the early or gestosis in late pregnancy. The intake of synthetic gestagens also affects its concentration.
There are cases in which the level of gonadotropin rises without pregnancy. Its growth is stimulated by:
- tumor diseases in the digestive tract;
- neoplasms in the testicles;
- Tumors in the uterus, lungs, kidneys;
- taking hCG drugs.
Also, the hCG value can be large with cystic drift. This is a situation in which the embryo does not develop, but the chorionic villi begin to grow actively. It can transform into a malignant tumor. Therefore, it is important to remove it in time.
Having received the first positive results of the analysis, it is important to monitor the intensity with which the concentration of the hormone increases. The hCG table makes it possible to verify whether the calculated gestational age corresponds to that determined in the laboratory. And growth dynamics determine the uterine location and viability of the embryo.
Reasons for lower hCG levels
There are frequent cases when the concentration of the hormone of pregnancy is reduced. The safest situation is when the timing mismatch can be caused by an error in the calculations. This often happens in women with an irregular cycle. After all, the date of ovulation in them is quite difficult to determine. Deviations in 5-7 days will already be very noticeable. To confirm that everything is normal with pregnancy, the dynamics of hCG will help. If the concentration of the hormone doubles every 2-3 days, then there is no reason for concern.
In the early stages, a decrease in hCG levels can be caused by:
- the threat of termination of pregnancy (with detachment of the placenta, the hormone level may decrease by 50%);
- improper implantation of the embryo (it can attach in the fallopian tubes, cervix, ovaries, or even in the abdominal cavity);
- Frozen pregnancy, in which the fetal death of the embryo occurs.
In the second or third trimester, the concentration of the hormone may also decrease. In this case, the blood donation is not in order to determine the timing. HCG can talk about placental insufficiency. If the amount of the hormone is reduced, then this may indicate a violation of the blood supply between the fetus and the mother. But to diagnose one result of the analysis is wrong.
Also, the concentration of the hormone will be less during fetal death. To confirm the diagnosis, an ultrasound scan is necessary. When pregnancy is delayed, the concentration of chorionic gonadotropin also decreases. This is due to the fact that the functions of the chorion gradually fade away.
Analysis Preparation
Despite the fact that hCG can be positive already a few days before the expected date of menstruation, gynecologists recommend waiting for a delay. At this time, by the exact result, it will be possible to understand whether fertilization has occurred.
For diagnosis, the technician takes venous blood. Therefore, it is important to go to this study on an empty stomach. Blood sampling is carried out in the morning. The night before, you need to abandon the use of fatty foods. Also, intense physical exertion should be avoided.
Before the study, you must warn the doctor about taking various medications. Some of them may affect non-test results.
If a woman was stimulated with ovulation and injected with the synthetic hormone hCG, then it is better to wait a bit with blood donation. After all, the body will need time to completely remove it. In this situation, it is advisable to wait a few days after the delay and pass the analysis at least twice in 1-2 days. This will allow you to track the growth dynamics of hCG by weeks and confirm that pregnancy has occurred.
Abnormality: is it worth it to panic
Not always a woman gets a result that matches her gestational age. In this case, she needs to immediately go to the gynecologist, even if she has not had time to register. In each situation, it is necessary to understand individually. An increased level of hCG can indicate both a multiple pregnancy, an incorrectly established period, and various problems. The doctor should prescribe additional tests to check if everything is normal with the woman. But first of all, it is necessary to conduct an ultrasound examination.
With a low concentration of the hormone, you can not do without consulting a doctor. The doctor will help to clarify the gestational age and check whether it meets the parameters determined in the laboratory. Given that the level of hCG decreases with improper implantation of the fetal egg, with the threat of a miscarriage or a dead pregnancy, it becomes clear why the specialist prescribes additional examinations: it is better to play it safe.
First of all, such women go to ultrasound. Depending on its results, it is determined whether something threatens the expectant mother and her baby. If a fetal egg is not found in the uterus, but the hCG exceeds 1000 units, they speak of an ectopic pregnancy. In this case, the fetal egg must be removed urgently.
With a threatening spontaneous abortion, preserving therapy is prescribed. Often, a woman should be in a hospital under the supervision of doctors until her condition improves.
If the hCG level does not noticeably coincide with what it should be at such a time, and the ultrasound does not visualize the heartbeat, this suggests that the embryo may have stopped developing. Further tactics of action depend on the term. If after a delay no more than 1-2 weeks have passed, then the analysis must be retaken in dynamics. Perhaps ovulation occurred later, and the estimated gestational age does not correspond to the real one.
Re-analysis
What does hCG mean, we figured it out. A study of its level can be carried out after 2-3 days in the first weeks of pregnancy. If it doubles, then there is no cause for concern. But what if the indicators increase very slowly? In such a situation, it is better to consult a doctor. Only a specialist can find out the reason that led to the fact that the concentration of the hormone does not increase in proportion to the term.
Most often, poor dynamics are observed with an ectopic pregnancy. The concentration of the hormone may increase, but there is no question of doubling it every 2-3 days. The shell of the embryo produces hCG, but not as actively as it does with normal egg implantation. As a rule, with an ectopic pregnancy, the level of hCG can increase by 2 times per week.
Dynamics may also deteriorate if there is a threat of miscarriage. In this case, it is important that the woman is assigned an adequate preservation therapy on time. In most cases, pregnant women are prescribed progesterone drugs (Dufaston, Utrozhestan) and strict bed rest is recommended. Doctors also prescribe antispasmodics and mild sedatives.
With a frozen pregnancy, hCG will not grow. If you take tests with a certain frequency, then you can see that its level is falling. The shorter the gestational age at the time the embryo stopped developing, the faster the rate will decrease. But in all cases, the study is preferably carried out in the same laboratory.
Express diagnostics
You can determine whether you managed to get pregnant, and at home. For this, special tests are used that respond to the presence of a hormone in the urine. Some manufacturers produce devices that allow you to find out approximate dates. HCG in the urine increases as well as in the blood. But such tests are not cheap.
Even with the help of such a home diagnosis, you can accurately determine whether fertilization of the egg has occurred. How pregnancy develops can be judged by the intensity of the color of the strip on the test. If on the first day of the delay it can be weak and hardly noticeable, then after a week it will have the same color as the control strip.
But if it does not get brighter, then this is an occasion to donate blood to determine the level of the hormone. After 6 weeks (counting from the last menstruation), it will already be possible to see an embryo and a heartbeat on ultrasound. The lack of dynamics may indicate a frozen pregnancy or an ectopic implantation of a fetal egg. But to draw such conclusions without ultrasound diagnosis and hCG testing for weeks is impossible. It is also worth noting that different tests may differ in sensitivity and dye concentration.
Features of the interpretation of the results
Despite the fact that when you receive a form with analyzes, a woman can see both her indicators and the hormone norm for each period, it is not worth interpreting them yourself.
For any deviations, it is important to assess the general condition of the pregnant woman. Additional diagnostic methods become mandatory. In any case, an ultrasound scan will be needed. Only with such a study can you see a fetal egg and an embryo, if they are in the uterus. With the help of ultrasound, an ectopic pregnancy is also determined. The absence of a fetal egg in the uterus and the accumulation of free fluid outside it will testify to it.
Having received too low hCG results, do not immediately despair. It is important to look at the dynamics and see the growth of indicators. Before donating blood, it is necessary to clarify the estimated gestational age. If this is not done, then the laboratories may not indicate the exact results, but simply write that the concentration of the hormone is greater than a certain indicator (for example, more than 1000). Indeed, in this case, the laboratory assistant simply determines whether there is a pregnancy. When indicating the week of pregnancy, the study will already calculate the exact numbers to check whether the expected dates correspond to those that were determined in the laboratory.
In addition, a woman should know signs that may indicate problems. These include pulling pains in the lower abdomen and back, smearing brown or spotting, a marked deterioration in well-being.