Pregnancy blood test is a procedure that is necessary to identify existing pathologies. It also allows you to determine the very presence of pregnancy, because it reveals the presence of a hormone called “chorionic gonadotropin” (hCG) in the woman’s blood.
In a situation where conception has not occurred, this substance is not produced in the human’s body, since its appearance is associated with the formation of chorion. This is a tissue that occurs between the endometrium and the zygote after attachment of a fertilized egg to the uterine wall.
Pregnancy Blood Test Basics
Blood is the most important indicator of a state of health. Its regular check during the expectation of the child allows you to determine any changes in the systems and organs, as well as establish 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 sure way to establish the fact of conception of a child. Rapid pharmacy tests used at home, even with high sensitivity to the human chorionic gonadotropin (hCG) produced by the female body, have a high degree of error, leaving a chance for an erroneous result.
You can pass pregnancy blood test 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 hCG hormone in the body rises so much that it can be “fixed” by an express test.
This test is prescribed not only to confirm the beginning of pregnancy, but also in order to exclude the likelihood of a baby developing outside the uterine cavity and early developmental pathologies. Pregnancy blood test also allows you to establish the exact age of the developing fetus.
Reasons for the Blood Study
Prtegnancy blood test can show the presence of pregnancy already on the sixth day after a successful conception. Whereas a standard pregnancy test in some cases can give incorrect results. Therefore, tests during pregnancy are prescribed to determine the following conditions:
- Establishment of the fact of conception
- Hormone assessment for malfunctions
Tracking abnormal pregnancy types:
- Frozen – in this case, at a certain stage, the embryo stops its development.
- Ectopic – in this situation, the zygote is attached not to the uterine wall, but in the fallopian tube.
A blood test also shows the presence of infections, other types of impaired functioning of the body and diseases such as:
Any of these diseases is a danger not only to the body of the woman herself, but also to her unborn child. Therefore, if there are deviations in the results of a blood test, the doctor directs the patient for an additional examination.
Change in hCG Levels during Pregnancy
After the physical onset of conception, the level of hCG in the female body begins to increase. Every two to three days its concentration almost doubles. It reaches its highest level at 8–11 weeks, and then it begins to gradually decrease.
The first analysis can be passed on the 6th day of the estimated delay, but the result will be more accurate on the 11-12th day. Therefore, doctors recommend checking blood two to three times (after two days each).
Control of hCG level allows to track the dynamics of pregnancy, the appearance of pathologies, etc.:
- With an ectopic pregnancy, the level of the hormone practically does not increase.
- If the development of the embryo is frozen, then the level of hCG drops from the moment of its death.
Typically, the result of the analysis is evaluated according to a special medical table a special table. In the first and second weeks, the concentration of hCG can range from 25 to 700 units. At the peak of the value it can reach 18,000–240,000 units. At the end of the gestation period its level is 2,179–60,000 units.
Other Blood Tests during Pregancy
After establishing the fact of conception, the doctor directs the patient to other blood tests:
- Coagulability test
- Hepatitis and HIV test
- TORCH infections blood test
- A test on genetic pathologies
- Rh factor and blood group (if they have not been previously determined)
- The test on the content of hormones produced by the thyroid gland
- Antiphospholipid syndrome test
- A blood test on STDs
Reasons for Abnormal hCG Hormone Level
Normally, after pregnancy, the level of chorionic gonadotropin should gradually increase. If it decreases, then the doctor may suggest the presence of such problems as:
In the early stages:
- Fetal death
- The likelihood of spontaneous abortion
- The absence of an embryo in the fetal egg
- At a later date:
- Placental abruption
In some cases, a low level of hCG may be associated with an incorrectly calculated gestational age. Therefore, in order to establish the exact cause of the low level of the hormone, pregnancy tests are usually performed in the early stages, as well as several types of other examinations.
Elevated hCG Level Occurs Because of
- multiple pregnancy
- diabetes of a pregnant woman
- intake of synthetic progestogens
- fetal pathologies (Down syndrome, multiple malformations)
- if the gestational age is incorrect
Low hCG Occurs With
- frozen pregnancy
- ectopic pregnancy
- delayed fetal development
- placental insufficiency
- threatened miscarriage (hCG reduced by more than 50%)
- fetal death (in the II-III trimester of pregnancy)
For non-pregnant women and for men, elevated levels of hCG may be a sign of tumor diseases of the gastrointestinal tract; testicular tumors; neoplasms of the lungs, kidneys, uterus; cystic drift; with an abortion (after 4-5 days).
Preparation for the Pregnancy Blood Test
Before passing hCG tests, the following preparation is necessary:
- Do not eat for 7–8 hours before the procedure
- Limit the intake of any fluid a few hours before the examination
- It is also necessary to warn the doctor about taking any medications.
- Statistics show that the highest concentration of hCG in the blood is observed in the first half of the day, so usually the doctor prescribes such an analysis early in the morning.
- If the recommendations are not followed, pregnancy blood test may show an unreliable result. So, additional procedures will have to be carried out.
When to Pass Pregnancy Blood Test?
Pregnancy blood test can be done on the 3-5th day of the delay of menstruation or on the 12th day after conception. However, the presence of hCG in the blood will be detected already on the 7th day after conception, Still, the accuracy of the analysis will be small and it will still be necessary to pass it again.
In order to trace the dynamics of hCG, it is necessary to check blood three times with a 2 days break, preferably at the same time.
While waiting for the baby to be born, the expectant mother often has to pass blood tests for various studies. All of them are important and necessary for an objective assessment of the state of her health and the course of intrauterine development of the child.
The hormone level of chorionic gonadotropin in a woman’s blood is the most accurate way to determine if she is pregnant. Keep in mind that HCG indicates not only the fact of the development of the embryo, but also the possible risks to the condition of the growing fetus, as well as deviations from the norm.