How is pregnancy determined by blood. Determination of pregnancy by the level of hCG. Determination of early pregnancy

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A modern rapid test, which is sold in a pharmacy, is a cheap, affordable and reliable way to find out about pregnancy. However, there are situations when a woman wants to know the result before she has a delay or if this is required by medical indications. Determination of pregnancy by blood test is the most informative and accurate method of diagnosing.

What is a blood test based on?

If conception has occurred, then the shell of the fertilized egg stimulates the production of a special hormone - human chorionic gonadotropin. The hCG hormone is also called the "pregnancy hormone". It is it that is determined both in conventional express tests and in a biochemical blood test. If fertilization does not occur, the hormone levels will not exceed the norm.

If the usual pharmacy tests allow you to identify the special condition of a woman from the first day of delay, then an analysis to determine pregnancy by hormone can be done even on the 6th day after conception, that is, a week earlier. However, for a more reliable result, it is recommended to determine pregnancy by blood at least after 3 days of delay.

HCG levels in a non-pregnant woman range from 0-10 mU / ml. From the first hours of pregnancy, the shell of a fertilized egg begins to produce a hormone and the values increase significantly, reaching a maximum by 12 weeks.

What is the analysis for?

A blood test to determine pregnancy is done in the following cases:

The need for earlier diagnosis of fertilization.
Determination of the degree of development of the fetus.
Timely detection of ectopic or missed pregnancy.
Determining the likelihood of a miscarriage.

How to take an analysis

For analysis, venous blood is taken, so it is better to do it in the morning, on an empty stomach. If blood sampling is done in the evening, it is recommended to refrain from eating 6-8 hours before the procedure. The results may be distorted if a woman takes some medications in parallel. You need to warn the doctor about this.

If the analysis is done before the onset of the delay, then the doctor will compare not only the absolute indicator of the concentration of the hormone, but also the dynamics of its change. With early diagnosis, the analysis will have to be repeated after 3 days. It is recommended to do repeated blood sampling in the same laboratory.

The analysis is done quite simply, you can order it in any private laboratory and even public clinics. The results are ready in 1-2 days. They need to be taken to a gynecologist so that he draws the right conclusions.

HCG norms

The sensitivity of pharmacy express tests starts from 15 mU / ml. If the hCG values are below this limit, only the control test strip will react, and the indicator will show a negative result.

In the first week of embryo development, the hormone level increases several times, and a blood test will help determine not only the fact of the increase, but also the quantitative content of the hormone.
In the third or fourth week, hCG can reach 1-30 thousand mU / ml.
The period of two-month development of the embryo is characterized by extremely high levels of the hormone. Its concentration can reach 30-200 thousand mU / ml.
Peak concentrations are recorded at 11-12 weeks, then the level of hCG gradually decreases.
In the second trimester, the level of the hormone is in the range of 20-60 thousand mU / ml.
In the third trimester, the values fall even lower - up to 6-10 thousand units. However, 1-2 weeks before the birth, the level of the hormone jumps up again.

Such wide ranges of values are explained by the individual course of each pregnancy. In addition, each laboratory conducts analysis based on a specific research method. Therefore, it is important to compare the results obtained not with generally accepted indicators, but with laboratory standards.

A woman is advised to wait for a delay in menstruation, since with an early analysis, the concentration of hCG may be insignificant. Then the doctor prescribes a second analysis to get the result in a few days and see the dynamics of the process. With an accomplished pregnancy, the numbers may differ several times, which will confirm the special condition of the woman.

By determining pregnancy by a blood test, you can not only find out the good news about its onset, but also track how well the fetus develops. For each week of pregnancy, there are boundaries for the normal concentration of the hormone. Deviation from these norms can be a symptom of incipient problems.

Causes of deviation from the norm

A blood test is the only way to determine the exact concentration of the hormone and draw a conclusion about the course of pregnancy. Deviations from the norm are observed in the case of:

Complications during pregnancy, for example, toxicosis.
Diabetes.
Multiple pregnancy.
placental insufficiency.
Wrong deadline.
Fetal pathologies.
A frozen embryo or ectopic attachment.
Premature birth or threatened miscarriage.

A blood test is an easy and quick way to find out if you are pregnant. Its advantage is that it is possible to control the course of the process by comparing the quantitative indicators of the hormone with the standards and its changes in dynamics. The level of hCG is an important diagnostic criterion for gynecologists in some controversial situations or in complicated pregnancy.

Nicole Hello! I heard that you can determine the gestational age by blood. How to do it? Where to apply?

You can find out about early pregnancy in various ways: with the help of a home test, ultrasound, and also by taking a blood test. The exact gestational age allows you to determine the analysis of hCG. A hormone called human chorionic gonatropin is secreted only in pregnant women. The embryo attached to the uterine membrane contributes to the production of hCG. Therefore, with successful fertilization, the result will be visible as early as 8-10 days after conception.

A blood test for hCG allows you to determine the exact gestational age and even exclude pathologies of intrauterine development. If the analysis is carried out at an early stage (2 weeks), then the value of the hormone level in the blood will not exceed 25 mU / ml. To confirm the results, the study is carried out again after a few days. If the fetus develops correctly, then the level of hCG will rise rapidly, and already at 3 weeks after fertilization, the indicators will reach 156-4870 mU / ml. In other words, the results of a blood test for the detection of human chorionic gonadotropin vary depending on the gestational age. So, the maximum value of hCG 20900-291000 mU / ml corresponds to 7-11 weeks of pregnancy. Starting from the second trimester, the level of this hormone in the expectant mother decreases. If you want to determine the gestational age by a blood test, then it is better to conduct studies from the second to the tenth week from the start of a missed period.

You can take a blood test for hCG in a private or state laboratory in the direction of a gynecologist. Conduct research in the morning, on an empty stomach. A day before the analysis, a woman is recommended to exclude physical activity, eating fatty foods.

For research take venous blood. The results will be ready within two days. After determining the level of hCG in the blood and obtaining a laboratory conclusion, the expectant mother should contact a gynecologist. Repeated analysis is carried out after a few days. This will allow you to set the exact gestational age and monitor the development of the fetus.

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What is HCG

The principle of operation of all test strips is based on the peculiarities of the "pregnancy hormone" - human chorionic gonadotropin. It is able to be released into the urine, it is on it that the reagent that is in the composition of all test strips reacts. The same hormone is present in venous blood, its presence can be determined already in the early stages. It appears in the blood within 6-8 days after successful fertilization. There are two options for this component:

alpha hCG - this hormone is quite difficult to distinguish in composition from LH, FSH or TSH (they are determined when deciphering biochemistry);
beta-hCG - plays a more important role in determining pregnancy.

With the help of this hormone, it is possible to monitor the development of the fetus throughout the entire period of its gestation, it also allows you to detect abnormalities and pathologies.

To get a reliable result, it is necessary to follow a certain procedure for preparing for blood sampling:

go to the laboratory in the morning, the stomach should be empty;
8 hours have passed since the last meal;
on the eve of blood donation for research, refrain from physical exertion and situations that can make you nervous;
if you are taking hormonal drugs, ask to make an appropriate mark on the form.

In a state clinic, it takes up to 2 days to process the results, and in a private clinic, the study is carried out in just a few hours. If you donate blood even before the delay of menstruation, then it is necessary to carry out two samplings of the material, with an interval of 2-3 days. This will allow you to look at the indicators of the hormone beta-hCG in dynamics. hormone levels can fall if the embryo has not attached to the wall of the uterus (such a pregnancy is called biochemical, that is, visible only according to the results of blood tests). If the level of hCG has increased, then the embryo has already begun to develop.

Features of changes in hCG and interpretation of the results

In women who are not in a state of expectation of a child, beta-hCG is not detected in the blood, or its value does not exceed 5 mIU / ml. If pregnancy has occurred, then you can notice an increase in the amount of the hormone exponentially:

1-2 weeks after conception, the amount of beta-hCG is 20-300 mIU / ml;
at 3-4 weeks, the value will already be more than 4800 mIU / ml;
the level of the hormone begins to fall only in the 3rd trimester.

These values will not be valid for all laboratories, since there are several methods for blood testing. Usually in private clinics, when deciphering the result of food, which week after conception corresponds to the resulting level of hCG.

If pregnancy is confirmed, but the amount of beta-hCG is below the minimum limit, then this may be due to:

ectopic location of the embryo;
the threat of miscarriage;
delayed fetal development;
incorrectly determined date of conception, only with irregular periods;
Edwards syndrome;
gestation of the fetus;
chronic placental insufficiency.

If the level of hCG is above the norm, then this indicates:

multiple pregnancy;
down syndrome;
toxicosis;
discrepancy between the terms determined by menstruation and the real ones;
increased blood sugar, diabetes in a pregnant woman.

If the pregnancy is not confirmed, and the hormone is detected in the blood, then this can become a symptom of: pathologies of the reproductive system, oncological lesions of the digestive tract and other diseases.

Currently, there are several methods that allow you to quickly and accurately determine the presence of pregnancy. One of the most popular of them are pregnancy tests sold in pharmacies. However, a more accurate result can be obtained by conducting a pregnancy blood test based on determining the level of the hCG hormone.

What is HCG

A special hormone that is not produced in the body of a man and a non-pregnant woman is human chorionic gonadotropin, called hCG for short. When pregnancy occurs, the membranes of the fetus, namely the chorion, begin to release the specified hormonal substance. The presence of gonadotropin in the blood allows you to accurately determine pregnancy by a blood test.

It is for this reason that this study is called a blood test for pregnancy.

Does a blood test show early pregnancy?

As follows from the instructions for a standard pharmacy test based on the presence of chorionic hormone in the urine, it is possible to obtain a reliable result on it no earlier than the first day of delay. You can determine pregnancy by a blood test already on the tenth day from the moment of fertilization, that is, approximately one week before the next planned menstruation. Thus, the possibility of conducting an earlier diagnosis when taking a blood test for pregnancy and the period at which this study can be carried out are the undoubted advantages of this method over the “usual” test from a pharmacy. However, such an analysis was created not only to ensure that impatient parents know the desired results as quickly as possible.

Pregnancy blood test: normal hCG levels

Many women are wondering what hCG indicators should be at a particular stage of pregnancy. It should be noted that each of these terms has a fairly wide range of normal values, which is why it is not always possible to find out how well the embryo develops. However, when taking a blood test for pregnancy twice or more, you can almost always get the correct results. In some situations, it is impossible for expectant mothers to conduct any other examinations, except for suggesting a blood test for pregnancy, therefore, in such situations, one has to rely only on the results obtained from a blood test for hCG.

The unit of measure for the level of chorionic hormone is honey/ml. For men and women who are not currently expecting a baby, the hCG value is less than 5. For pregnant women, the rate of this hormone is determined for each period of pregnancy separately.

Compared with the baseline, which is less than 5 mU / ml, the content of chorionic hormone in the blood of a woman carrying a child will always be increased. And in some cases, the level of this hormone increases even more than it should be at the corresponding gestational age. A significant increase in the level of chorionic gonadotropin occurs with a multiple pregnancy of the patient. In this case, the value of this hormone can exceed 1.5-2 times and even more than the normal level of hCG for each period of pregnancy.

Such a study as a blood test for hCG does not need to be carried out in every case of pregnancy. If the gestation proceeds safely, then there is no need to take this analysis. However, in any case, performing a blood test for hCG provides diagnostic information, on the basis of which it is possible to identify possible violations in the development of the fetus, select the necessary treatment, and, with the normal development of the child, please future parents with such information.

Throughout the entire period of pregnancy, expectant mothers are recommended to take many tests necessary in order to dynamically monitor their own health and the growing baby.

A blood test is the most common type of study, thanks to which it is possible to establish the conception of a fetus, determine its age, level of development, and the presence of pregnancy pathologies.

Basic information about a pregnancy blood test

Blood is the most important indicator of health status. Its regular delivery while waiting for a child allows you to determine any changes in systems and organs, as well as fix the conception of the fetus and the beginning of a new life in the mother's body.

A blood test for pregnancy is the most informative and surest way to establish the fact of conception of a child. Pharmacy express tests used at home, even with high sensitivity to the human chorionic gonadotropin (hCG) produced by the female body, have a large margin of error, leaving a chance for an erroneous result.

You can donate blood for pregnancy on the sixth day after the expected date of conception. It accurately confirms the presence of an embryo in the uterine cavity long before the level of the hCG hormone in the body rises so much that an express test can “fix” it.

This test is prescribed not only to confirm the beginning of an "interesting situation", but also in order to exclude the likelihood of a baby developing outside the uterine cavity and early developmental pathologies. Also, this study allows you to determine the exact age of the developing fetus.

The earliest term for determining pregnancy

If a woman knows the date of conception of the baby, she can visit the laboratory to donate the material a week later. If the expectant mother does not have exact data on the date of conception, this can be done within the first week after the delay in menstruation. At the very beginning of its development, after the embryonic egg is attached to the wall of the uterus, the amount of chorionic gonadotropin in the mother's body doubles every day.

If conception has occurred, this will show the level of hCG. Such a study allows you to set the age of the fetus not only in weeks, but also in days. This information, as well as data on the development of the baby, obtained using ultrasound diagnostics, make it possible to establish the expected date of birth as accurately as possible.

For research, the material is taken from a vein. The material sampling process takes a few seconds and does not threaten the health of mother and baby.

When should a pregnancy blood test be done?

This procedure is carried out at the beginning of the first trimester, from the first weeks of delayed menstruation, to confirm the fact of fertilization. If a woman trusts the rapid test, does not plan to terminate the pregnancy and feels well, you can wait a bit with going to the laboratory.

When registering, a woman must submit:

KLA (from a finger);
blood chemistry;
coagulogram;
material for HIV infection;
blood for hepatitis B and C;
detection of antibodies to syphilis;
testing for sexually transmitted infections.

In addition to mandatory studies, an additional expectant mother can be tested for hCG.

It is necessary if:

the doctor suspects an ectopic development of the fetus in a woman;
if a multiple pregnancy is established;
the age of a woman is over 35 years old and she is at risk for determining Down syndrome in a child;
in the anamnesis of the pregnant woman there are hereditary diseases (Down syndrome, Edwards syndrome);
there is a risk of miscarriage or miscarriage;
the expectant mother was exposed to radiation.

In the absence of these indications, you can check the level of hCG for a period of 12-14 weeks, or in the 2nd trimester at 15-17 weeks to confirm the normal development of the baby and the absence of pathologies. This is called a triple extended test and determines not only the level of gonadotropin, but also AFP and estriol.

Another important study prescribed to a woman during pregnancy is the determination of TORCH infections (cytomegalovirus, rubella, herpes, toxoplasmosis).

Conducting and deciphering the study

Hand over the material for research in the morning. It is recommended to give up breakfast, drinking alcohol, smoking, tea or coffee. The last meal should be in the evening, no later than 20-21 hours. To pass the analysis, you must contact the laboratory, saying the name of the study. How long the result will be ready and whether it is possible to get it urgently depends on the laboratory in which it is carried out.

You can take an analysis in any city, even in Krivoy Rog, even in St. Petersburg, in a private laboratory. No one will forbid you to contact the laboratories of a state clinic. But often there are long queues in state clinics, so it is important not to miss the deadline for passing the analysis indicated in the direction of the obstetrician-gynecologist observing the woman.

The cost of the test depends on the level of the laboratory and the speed of the result. In any case, its price is not high relative to its great information content and importance.

Deciphering the results of the hCG test is carried out using special tables that indicate the normal level of hormones by week of pregnancy. Such a table shows whether conception has occurred if the study is carried out at an early stage, and also whether the fetus has developmental pathologies if the test is carried out in the 2nd-3rd trimester.

Low levels of the hormone indicate:

probable fetal death;
stopping development, lagging behind its norms;
ectopic development of the embryonic egg;
re-carrying a child in the later stages.

High scores indicate the presence of:

suspicion of Down syndrome in a baby;
severe toxicosis;
overbearing a child.

Only a specialist from the laboratory or an obstetrician-gynecologist can decipher the results correctly. Self-interpretation of data is fraught with errors. If you get an unsatisfactory result, do not panic. There is always the possibility of an error in the conduct of the study, so it is re-assigned. It is advisable to repeat the study in the same laboratory as the first time.

Can a complete blood count detect pregnancy in the early stages?

A general blood test provides information about the health status of a woman and a baby. It shows the level of erythrocytes, leukocytes, platelets, monocytes, lymphocytes, hemoglobin, erythrocyte sedimentation rate (ESR), as well as the characteristics of other indicators. The rate of red blood cells for a woman carrying a baby (3.5-5.6) ∙ 10 to the 12th degree of cells / l, but this indicator does not allow you to determine whether a woman is pregnant or not.

Another important indicator is the level of hemoglobin. For a woman in an “interesting position”, its norm is 110 g / liter. Fluctuations in hemoglobin levels do not indicate the onset of a "pregnant state".

It is not visible in the general analysis of the onset of conception and in the level of leukocytes. Their growth while expecting a child is noted already in the second or third trimester due to an increase in immunity due to the bearing of the fetus. Causes an increase in leukocytes at the beginning of the "interesting situation" the presence of vaginosis, candidiasis, cystitis, colds, inflammatory processes.

Obviously, the indicators that a routine blood test allows you to know cannot confirm whether a woman is pregnant or not.

How else can such an analysis be useful?

A woman gives UAC every month while waiting for a baby. It allows you to assess the course of pregnancy and the health of the mother, not only by the level of hemoglobin, erythrocytes, or the number of leukocytes. Its task is also to determine allergies in pregnant women. Basophils are responsible for its detection. During allergies (or rhinitis of pregnancy, which many mothers face), their number increases. The growth of basophils can provoke an allergy to dust, animal hair and vitamins.

Another indicator that indicates the development of an allergic reaction is the number of eosinophils.

Blood neutrophils show the development of a bacterial infection in the body, the course of purulent processes, for example, tonsillitis, otitis media, meningitis.

Lymphocytes in the blood of pregnant women indicate a decrease in the level of immunity. During the bearing of the baby, the body of the expectant mother is subjected to a great load, causing a weakening of the immune system, which is reflected in the blood test.

The number of monocytes is important. These are large leukocytes, the number of which increases if the expectant mother catches a cold, falls ill with ARVI, influenza, or mononucleosis, which can be determined by the enlargement of the lymph nodes.

Important details on this topic can be found in the video:

Conclusion

While waiting for the birth of a child, the expectant mother often has to donate blood from a vein or a finger for various studies. All of them are important and necessary for an objective assessment of the state of her health and the course of the intrauterine development of the child.

The level of the hormone chorionic gonadotropin in a woman's blood is the most accurate way to determine if she is pregnant. HCG indicates not only the fact of the development of the embryo, but also the possible risks for the condition of the growing fetus, as well as deviations from the norm.

UAC is an equally important study that allows you to assess the condition of the expectant mother in dynamics and correct it if necessary.

If once again the doctor gave the pregnant woman a referral to the laboratory, you should not complain about the frequency of taking the KLA, and even more so, ignore it.