Blood Pregnancy Test: Everything You Need to Know


The developing technology is providing people with easy ways to get their work done from home. Similarly, there are many available simple methods which let you know if you are pregnant or not. There are home pregnancy test kits available in the market which help you sit at home and find out whether you are pregnant or not. But even after you have used these kits to test your pregnancy, your doctor might suggest you to get a blood pregnancy test done to get your pregnancy confirmed.

A Guide for Blood Pregnancy Test

pregnancy blood test

What is a Blood Pregnancy Test?

A blood pregnancy test is carried out to determine for sure whether a woman is pregnant or not. Some amount of blood is taken from the woman and then tested for HCG. There are basically two different types of blood pregnancy tests, also called pregnancy serum tests:

Quantitative HCG Blood Test – to measure the exact amount of HCG in your blood. A procedure called venepuncture is used to extract blood sample from a vein for a qualitative blood test. This test is instant and is done only once to know the level of HCG in the blood.

Qualitative HCG Blood Test – gives the confirmation of the presence of HCG, and a ‘yes’ or ‘no’ answer for pregnancy. Venepuncture is used even in this test to detect pregnancy. In this test, blood is drawn twice in a time span of 48-72 hours to confirm the pregnancy. This is as accurate method of testing, since there is a gap between the two tests in case of a false result on the first time.

You must now be wondering what this HCG exactly means, so basically HCG is the abbreviation for Human Chorionic Gonadotropin. The HCG blood test measures the level of HCG hormone present in the sample of your blood. This hormone is present during your pregnancy. There is also a huge difference in HCG blood tests and the HCG urine tests. Urine tests are mostly influenced by certain factors like dehydration and the time of day you take this test, whereas an HCG blood test will give you the exact result in if your HCG levels are low.


The HCG levels can be detected in blood approximately after 11 days of conception. And the levels continue to double every 48 to 72 hours and reach their peak during the 8 to 11 weeks after conceiving. They then decline and remain steady for the rest of the pregnancy.

Why is the HCG Blood Test Performed?

This test is basically performed to confirm your pregnancy, determine the approximate age of the fetus, to know if you are carrying multiple babies, diagnose an abnormal pregnancy: such as ectopic pregnancy, diagnose a potential miscarriage, to make sure that the fetus is not harmed by any medical treatments, and to screen for down-syndrome.

How is the Test Performed?

A technician or a nurse first collects blood from the vein of either your forearm or hand, using a syringe or vial. The tests are carried out in different labs and after the testing is complete, reports will be sent to the doctor or you may have to collect the reports by yourself. The blood test reports will be explained to you by your gynecologist or lab technician. This test helps to identify pregnancy hormone in your blood and also determines the levels of HCG if your pregnancy is confirmed.

How are the Results Interpreted?

Results from a quantitative HCG test or blood pregnancy test will show how the HCG levels rise rapidly during the first trimester of pregnancy and then slightly decline during the last weeks of pregnancy. Abnormal results, on the other hand, can mean a variety of things, where higher than normal levels may indicate:

  • More than one fetus, i.e. twins or triplets
  • Infection or malignant tumors of the uterus
  • Non-cancerous tumors of the uterus
  • Breast cancer
  • Lung cancer
  • Choriocarcinoma
  • Ovarian cancer
  • Testicular cancer (in men)
  • Sometimes just an indication of a normal pregnancy

Lower than normal levels may mean:

Accuracy of Blood Pregnancy Test

No test is said to be 100% accurate. To get the accurate result of HCG test, one should take the test 7 days after ovulation. Sometimes, certain medications like Profasi, Pregnyl, and Pergonal, may interfere with the HCG results. Smoking marijuana can also cause for the elevation of HCG levels in your blood. Therefore, HCG test can give both false-negative results and false-positive results of pregnancy.


False-Negative Resultsconducting HCG too early can lead to false-negative results. Which means the results may show that you are not pregnant even though you are pregnant. This can happen if the test fails to identify HCG hormones. Therefore, it is suggested to perform this test a week after ovulation, or repeat the test again after 42-72 hours.

False-Positive Resultsin very rare cases, it may happen that your test results show that you are pregnant when in reality you are not. This certainly might happen if you are under some kind of medications which can increase your HCG levels.

Medications that can Affect the Accuracy of the Results

Several medications can affect the accuracy of a blood pregnancy test. Some of them are listed as follows:

  • Hypnotics- a prescription of sleep medication can affect levels of HCG.
  • Promethazine- a medication used to treat allergic symptoms, cold or a cough or motion sickness can increase or decrease levels of HCG.
  • Medications which are used to prevent seizures.
  • Medicine which is taken to treat Parkinson’s disease.
  • Prescription that contains HCG like Pregnyl, APL, Profasi, Chorex, Novarel, or Ovidrel.
  • Phenothiazine drugs such as Chlorpromazine or Thorazine

How soon can Blood Test Detect Pregnancy?

HCG in your blood can be detected when implantation in the placenta takes place, i.e. ten days after you missed period. The HCG levels can rise during the first two months of pregnancy. This shift of hormones can make it easy to detect your pregnancy. It would take two days for you to receive your reports after taking the test. In the early stage, blood is taken 48 hours apart to keep the results accurate.

Risks of Taking Pregnancy Test Using Blood

Since a very small amount of blood is drawn for a blood test, the risks can range from none to one. Yet in very rare cases, certain risks might pop up after a blood test is performed, which are listed below:

  • One possible risk of taking a blood test for pregnancy is a false-positive result which can occur due to an exposure of certain medications, taken by the mother
  • Minor bruising where the needle is inserted
  • Lightheadedness
  • Fainting in rare cases
  • Infection in rare cases
  • Haematoma where blood gets accumulated under the skin

How much does Blood Pregnancy Test cost?

The expense for a blood pregnancy test will vary depending on the clinic you choose. A good and well equipped clinic could cost you around 1,000 rupees, and a general clinic may cost you around $49. And, if the results are uncertain (HCG level between 5mIU/ml and 25mIU/ml), a retest will be required in a few days, which will in most cases incur an additional fee. On the other hand, you can purchase 10 early detection pregnancy test strips for about $3-$6, which will allow you to test several days in a row if necessary.


Can Blood Pregnancy Test be wrong?

Like we have discussed above, the results of a blood test can be 98-99% accurate. The results may sometimes be false due to several factors like interference of medications, early pregnancy test, or if the women are on fertility drugs. No test can ever be 100% accurate. But to confirm a pregnancy, every doctor recommends a blood pregnancy test after you’ve done the regular urine test.

Can you Perform this Test at Home?

A blood test can only be performed at a diagnostic office under the guidance of a gynecologist. Since it involves various steps and a set pattern is used to detect HCG hormone in your blood, it can only be performed in a clinic. You may try other pregnancy test methods like urine test at home. But even after you’ve done a urine test, it is important to get a blood test done in the later stages, since blood test provides wider information regarding your pregnancy.


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