16 Important First Trimester Blood Tests You Should Be Aware Off

16 Essential Blood Tests During First Trimester of Pregnancy

Medically Reviewed By
Dr. Sabiha Anjum (Gynecologist/Obstetrician)
View more Gynecologist/Obstetrician Our Panel of Experts

The very first step that confirms a pregnancy is a blood test. Then follow a series of checkups to ensure you and the baby growing inside you are healthy. These include some more blood tests which are done each semester to check for infections, diseases, etc. In this article, we shall focus on the common blood tests done in the first semester. If you have just confirmed your good news, you must read through this article to have an idea of what lies ahead for you.

Common First Trimester Blood Tests

Your doctor will suggest a few blood tests during your first prenatal visit. These tests are optional, but it is advisable to go for the tests as it gives the doctor an idea about your health. These blood tests may also highlight any potential problem that you may encounter during your pregnancy.

1. Blood Group

It is important for the doctor to determine your blood group in case you need a blood transfusion anytime during the pregnancy.

2. Rhesus (Rh) Factor

It is crucial for the doctor to determine if you are RhD positive or negative. If you are RhD positive, that means that a protein called D antigen is present on the surface of your red blood cells, whereas if you are RhD negative, then you don’t have the protein. In this case, your doctor may give you a shot of Rh immune globulin once during the pregnancy and another after the baby’s birth. This shot is particularly necessary if you are an Rh-negative mother carrying an Rh-positive baby (which the baby may have inherited from her father). In this case, if some of your baby’s blood enters your bloodstream, then your body will produce antibodies that will attack your baby’s red blood cells. To avoid this, your doctor may advise you to take immune globulin shot during the 28th week of pregnancy.

3. Iron Levels

A blood test is also done to check your haemoglobin levels, which determines if you are iron deficient. During pregnancy, your body needs iron to produce enough haemoglobin that can carry oxygen to all parts of your body and the baby. Hence, if your blood test shows that you are iron deficient, then your doctor may prescribe iron supplements to make up for the deficiency.

4. Blood Sugar

Your doctor will be interested in checking your blood sugar through a blood test if you are overweight or if you have a history of diabetes. A blood test is done to determine if you have gestational diabetes.

5. Hepatitis B

Blood test helps the doctor to determine if you are a carrier or Hepatitis B. Now, this is critical because if your baby gets Hepatitis B from you, it may cause severe damage to her liver. In this scenario, the doctor will inject your baby with antibodies to protect her from Hepatitis B as soon as your baby is born.


It is vital that all expecting mothers get tested for HIV and AIDS. If HIV or AIDS is detected in a mother-to-be, necessary steps can be taken to ensure that the same does not get transmitted to the baby.

7. Syphilis

Syphilis poses a health risk to the mother as well as the baby in the rare event that the mother is infected. If tested positive, the mother may be recommenced antibiotics to treat it.

Which Other Blood Tests Should Be Done?

You may have to take some additional tests during the first trimester of your pregnancy. They are as follows:

Other tests during pregnancy

1. Screening for Thyroid

During the first trimester of pregnancy, your doctor would want to determine your thyroid level. If you have hypothyroid or hyperthyroid, you will be kept under close monitoring throughout the pregnancy to ensure that your thyroid hormones stay under control as it is essential for the proper development of the baby.

2. Rubella (German Measles)

Catching rubella during pregnancy can hurt your baby’s heart, sight, and hearing. While most women develop immunity against German measles as kids, either through vaccination or by contracting it during childhood, there may be ones who have never got it and are at risk of getting it during pregnancy. They must be very careful and stay away from anyone who has measles. There are no medicines or injections at this stage to prevent rubella.

3. Combined Screening Test

This test is a combination of a blood test and a nuchal translucency scan that is done towards the end of the first trimester to determine if the baby has any genetic abnormalities like Downs syndrome. It is done alongside your normal scan for more specific results.

4. Cytomegalovirus (CMV)

Although this blood test is not mandatory, it could be prescribed to check for a CMV infection. A mother infected with the CMV virus can pass it on to the foetus, and it could have severe implications for the developing baby like hearing loss or mental retardation.

5. Hepatitis C

Hepatitis C blood test is optional and usually suggested if you believe that you may be infected by Hepatitis C. This test is only done if the doctors observe any symptoms of Hepatitis C from you.

6. Herpes Simplex Virus (HSV)

This is another test that is not prescribed usually, but if your doctor thinks it is important for you, he/she may ask you to get an HSV blood test. Herpes is a common and very painful infection that takes place in the mouth or the genital area. If not treated, it can cause brain damage in babies. The blood test is done to check the presence of this infection in expecting mothers in case they show any symptoms of herpes. 

7. Sickle Cell Disease and Thalassemia

Test for sickle cell disease or thalassemia is done only in selective patients in the first trimester. Sickle cell disorder and thalassemia are two types of blood cell disorders that can make you anaemic and can be passed on to your little one.

8. Toxoplasmosis

A toxoplasmosis infection may be passed on to the unborn baby if the mother contracts the infection in the first trimester, or in the first few weeks before conceiving. Although the test is done selectively, it is prescribed to prevent organ damage, miscarriage, or even stillbirth due to the infection.

9. Screening for Vitamin D levels

A lack of the requisite amount of Vitamin D may cause weak bones or abnormal growth in newborns, and increase the risk of complications such as preeclampsia in the mother-to-be. A test to determine the levels of vitamin D is thus often conducted in the first trimester.

Which Blood Tests Are Done at Home or the Collection Centre, Safely?

Big hospitals have their laboratories, and blood tests are done in these well-equipped labs. These days, many renowned labs offer to collect blood samples from home to save the patients from the trouble of moving out of bed when not well.

Pregnant Woman at doctors'

Many people worry about the safety of blood samples being collected from home and transported to the labs for the test. They assume that there are high chances of the results getting skewed in this scenario. But so far, there is no definite evidence for the same.

Hence, all blood tests done at home or the collection centre are safe and accurate as long as you chose a reputed laboratory.

Can You Request Additional Tests?

There are few conditions for which tests are not offered as a part of first-trimester screening blood test routine. In the following cases, you may request an additional blood test.

Pregnant woman with cat

  • If you have a pet at home and you feel that you are in danger of being infected with toxoplasmosis which usually spreads through cat poop, soil or undercooked meat, then you must request your doctor to test you for the same. Toxoplasmosis can damage a developing baby or can be a cause of miscarriage. Hence, you must be careful.
  • If you are worried about being infected by Group B strep, you can ask your doctor to test you for the same in late pregnancy, around the 37th week. An infected mother can pass it on to her child, who may fall very ill soon after birth.
  • If you feel that you are at the risk of contracting Hepatitis C, then you should approach your doctor for a blood test. Your chances of contracting hepatitis C are high if you have injected drugs in the past, or have tattoos and body piercings.

Will You Be Tested for Blood Cell Disorders?

Yes, as mentioned before, you will be offered to test for blood cell disorders like sickle cells disorder and Thalassemia. These disorders can make you anaemic, and you may also end up passing it to your little one. Usually, all pregnant women who live in an area where these conditions are common are offered to take the blood cells disorder tests. If you have a history of anaemia, you may as well let your doctor know in advance and offer to take up the blood cells disorder tests.

Apart from these commonly asked questions, you must also bear in mind certain things when getting your blood tests done.

Things to Remember When Getting a Blood Test Done During the First Trimester

These points will help you manage any anxiety you may experience while getting blood tests done during the first trimester.

  • Ask someone to accompany you for the test.
  • Be a 100% sure that the technician removes a brand new needle from a sealed package.
  • Carry some water and snacks just in case you need an energy boost.
  • Check well in advance if fasting is needed for any of the blood tests.
  • Try relaxing methods like listening to music or meditating to calm your nerves.

Blood tests are a routine procedure for hospitals as it helps the doctor gage any underlying medical conditions that you may have. Many of the issues, when detected early, can help the mother and child as the appropriate medication can be started at the earliest.

Also Read: Quadruple Marker Test During Pregnancy

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