Pregnancy hormone analysis
There are several ways to determine pregnancy by analyzing the levels of human chorionic gonadotropin (hCG) in a woman's body. This hormone is usually produced after the fertilized egg attaches to the uterine wall and continues throughout all stages of pregnancy.
To check for pregnancy using a urine sample, the test can be performed one week after a missed period. Urine testing kits are available for use at home and provide results with an accuracy of 97% to 99% if used correctly, which is similar in accuracy to laboratory results.
While blood tests are only done in laboratories and are considered more sensitive in detecting the pregnancy hormone, they can determine the presence of pregnancy before a missed period. Moreover, blood tests provide up to 99% accuracy and are often used to confirm urine test results.
What is the pregnancy hormone in the blood (HCG)?
Human chorionic gonadotropin, also known as the pregnancy hormone, is produced by the placenta during pregnancy. This hormone plays a pivotal role in confirming pregnancy and is used in home pregnancy tests or laboratory tests.
When does the pregnancy hormone appear in the blood?
Once the egg is fertilized, the placenta begins to secrete the pregnancy hormone (HCG), which plays an important role in the continuation of the pregnancy. This hormone supports the ovaries to produce sufficient amounts of the estrogen and progesterone hormones necessary to support the stability of the fetus.
The pregnancy hormone is associated with several vital functions during pregnancy, as it contributes to supporting the corpus luteum, which plays an effective role in secreting progesterone, which is necessary to thicken and nourish the uterine wall with blood vessels, which helps provide a suitable environment for the growth of the fetus in its early stages.
The pregnancy hormone also suppresses the mother's immune system, which ensures the fetus is protected from immune attacks during the first months of pregnancy.
In a medical context, hCG is used to stimulate ovulation in women and enhance testosterone secretion in men.
What are the functions of pregnancy hormone?
The pregnancy hormone plays a vital role in supporting pregnancy and ensuring its stability, as it performs many essential functions, including:
– Stimulates the corpus luteum to produce progesterone.
- It supports the uterus in its preparation for expansion in line with the growth of the fetus.
- It contributes to the formation of new blood vessels inside the uterus.
- It plays a role in the growth of the umbilical cord that connects the fetus to the mother.
- It helps in the development of the cytotrophoblast, which benefits the fetus.
- Suppresses the mother's immune responses against the fetus.
- Supports the healthy growth and development of the fetus’s organs.
All these factors confirm the importance of the pregnancy hormone for the mother's health and the growth of the fetus.
How is the pregnancy hormone tested?
To detect the pregnancy hormone, a urine test or blood test can be used. In home pregnancy tests that use urine, the pregnancy hormone causes lines to appear on the test device.
It should be noted that a home urine test may be less accurate than a blood test, and may not give an accurate determination of the hormone level, especially if it is performed early, which may lead to a false negative result.
It is important to know that the ideal time to conduct a blood pregnancy test is one week after fertilization, and one week or five days before the menstrual period, but it is preferable to wait until the menstrual period for more accurate results.
A home pregnancy test can detect hCG 12 to 14 days after conception. A blood test can detect the hormone 11 days after conception.
Urine analysis cannot detect pregnancy a week before the menstrual period, unlike blood analysis which can detect pregnancy before symptoms appear. To increase accuracy, it is recommended to repeat the analysis over different days.
There are two types of pregnancy tests: a qualitative test that shows the presence or absence of the pregnancy hormone, and a quantitative test that determines the level of the hormone in the blood.
What is the level of pregnancy hormone in the blood?
During pregnancy, pregnancy hormone levels undergo significant changes in the blood circulation, increasing significantly during the first three to four weeks, doubling approximately every three days, before reaching their peak between the eighth and eleventh week of pregnancy, and then gradually decreasing thereafter.
High levels of the hormone at the beginning of pregnancy contribute to providing very important data about the health of the fetus and the course of pregnancy. After birth, this hormone completely disappears from the blood.
In terms of diagnosis, a pregnancy test shows a positive result when the level of pregnancy hormone is higher than 25 units per milliliter, and a negative result when it is less than 5 units per milliliter. In cases where the level of this hormone is between 5 and 25 units per milliliter, the test is repeated to confirm the presence or absence of pregnancy.
The gestational sac can be seen on ultrasound when hormone levels are between 1000 and 2000 units per milliliter.
It is worth noting that the pregnancy hormone is generally high in cases of monozygotic twin pregnancies, while its levels decrease when the fertilized egg attaches outside the uterus, as in cases of ectopic pregnancy, where it is usually in the fallopian tubes.
What happens when the level of pregnancy hormone rises and falls?
As pregnancy progresses, the level of pregnancy hormone in the body gradually increases, usually doubling every two to three days. As pregnancy continues, the time required for the hormone level to double may extend to four days.
A significant decrease in the level of the pregnancy hormone may indicate the occurrence of problems such as miscarriage, whether it has already occurred or there is a possibility of it occurring, or a problem with the egg such as a bad egg, or that the date of pregnancy has been estimated inaccurately.
However, the pregnancy may continue normally and the baby may be healthy even with low levels of hCG. In these cases, fetal ultrasound is a more effective tool for checking the health of the fetus.
If the hormone level is abnormal, taking a long time to double or is lower than the normal rate, this may indicate an ectopic pregnancy.
On the other hand, excessive increase in pregnancy hormone levels can be caused by inaccurate estimation of gestational age, molar pregnancy, multiple pregnancy, or certain types of cancer such as lung, breast, and kidney cancer.
