How long does it take to get pregnant before you can do a blood test?

In modern society, there are many ways to test whether a woman is pregnant. The most convenient way is to go to the pharmacy and buy a pregnancy test stick or paper. However, the most accurate method is to go to the hospital for a blood test, because the blood test can effectively detect the hcg value in the female body, and the hcg value is an important indicator to infer whether a woman is pregnant. How long after pregnancy can I have a blood test?

How long after pregnancy can I have a blood test

In order to determine whether you are pregnant early, you need to check the hCG level in the blood. If the hCG value in the blood is greater than 5, you can confirm that you are pregnant. Generally, the earliest HCG increase can be detected 8-10 days after intercourse. The blood HCG values ​​of different women and different days of pregnancy are different. Therefore, you can go to the hospital for a blood test 8-10 days after having sex to see if you are pregnant.

After a woman is confirmed to be pregnant, she should have blood drawn for hCG testing three times in a row. The test must be done every other day and the three values ​​should be compared. If they can basically double, it means the fetus is normal. If it does not basically double and the value is relatively low, we need to supplement hCG, usually by injecting 2000 units per day.

After a normal woman becomes pregnant, the hCG level in her blood increases rapidly. 35-50 days after pregnancy, hCG can rise to greater than 2500 IU/L. It can reach 80,000 IU/L in 60-70 days. The hCG value reaches its peak at 60-80 days of pregnancy, then gradually decreases, reaching the lowest at 160-180 days of pregnancy, but is still significantly higher than normal, and then rises slightly and continues to maintain until delivery. In twin pregnancies, blood hCG is more than doubled that of a single pregnancy.

If the monitored hCG level is too high, even exceeding 200,000 at 30 or 40 days, it can be considered whether it is a hydatidiform mole, which requires further pathological analysis to confirm.

If hCG doubling is not good, whether it is too high or too low, you need to closely monitor the development of the fetus and deal with any abnormalities immediately to avoid causing greater harm to the fetus or yourself.

Therefore, if women suspect that they are pregnant, they should go to the hospital for examination as soon as possible and should not be afraid of blood draws or blood tests.

When should blood hCG be tested?

1. Confirm pregnancy - the earliest can be 8-10 days after intercourse

The best time to test hCG blood is 8-10 days after intercourse. At this time, the test can be used as a pregnancy test to confirm pregnancy. At the same time, in the first 3 months of pregnancy, this test can also be used to diagnose single or multiple pregnancies.

2. Diagnosis of abnormal pregnancy - test whether the hCG content doubles every 2 days

After a woman becomes pregnant, an increase in the β-hCG value in the blood can be detected from the 9th to 11th day, and the β-hCG value can double every two days thereafter. If the test shows that the increase rate is slow for two consecutive times, it may be caused by factors such as ectopic pregnancy, abnormal embryo or intrauterine growth retardation.

If the value is too low, the hCG concentration in the serum is much higher than the value in the corresponding month of normal pregnancy. Therefore, this difference can be used as an auxiliary diagnosis of hydatidiform mole, which is usually performed in the first 3 months of pregnancy.

3. Down syndrome screening - 15-20 weeks of pregnancy

Down syndrome screening detects the levels of AFP and β-hCG in venous blood and comprehensively calculates the risk of the fetus having Down syndrome. The best time to do this test is between 15 and 20 weeks of pregnancy.

4. Determination of miscarriage: 4 days after delivery or 13 days after artificial abortion

Since the fetus has been delivered, the woman's blood hCG test should return to normal 4 days after delivery or 13 days after artificial abortion.