Routine blood tests during first trimester

What blood tests are offered during the first trimester?

Blood tests are an important part of your routine antenatal care in pregnancy. The first set of blood tests are conducted right after your pregnancy is confirmed. You shall be offered some or all of the tests mentioned below by your OB, they may even prescribe additional tests. These are conducted to check your blood group, whether you have any infections or diseases and to ascertain if your baby has any fetal abnormalities.

All blood tests are offered as optional. Your doctor will explain why each of the tests is conducted and you can decide whether to have them or not. It’s highly recommended that you conduct all tests prescribed by your doctor.

It is natural to be worried about getting tests done, however you should know that these tests provide important information to your doctor about the pregnancy and help them diagnose any potential complications that may occur during the pregnancy term. The following tests will be offered as a part of the first screening.

Blood group

Your blood group is important for the doctor to know, just in case you require blood transfusion during pregnancy or birth. Blood group O is commonly known as the universal donor and blood group AB is considered to be a universal recipient.

Rhesus (Rh) factor  

This is an important test as your doctor needs to know your rhesus status ie positive or negative. If you are rhesus positive also known as RhD positive, you have a certain protein on the surface of your red blood cells (immunogenic D antigen of the Rh blood group system).

If you are RhD negative and your partner is RhD positive, then there is a fair chance that your baby maybe RhD positive too. In this case, your immune system starts attacking the red blood cells of the baby. Injections of immunoglobulin, given during week 28 prevents this from happening.

Haemoglobin level (Hb)

A basic blood test determines your Hb level (normal range 12.0 – 15.5 gram per deciliter). A low level of haemoglobin indicates an iron deficiency. Your body requires iron to create haemoglobin to carry oxygen in your red blood cells.

If you are anaemic due to Iron deficiency, your doctor will prescribe diet changes and prescribe iron supplements to boost your Iron levels. Routine blood tests will be conducted during the course of the pregnancy to keep the Hb levels in check.

Hepatitis B

A blood is the only way to determine if you are a carrier of Hepatitis B virus. If you pass on the virus to your baby during the pregnancy or after birth, the baby will have to be protected using vaccines and antibodies. A blood test is generally done at one year of age to ascertain if the baby has Hepatitis B.


Syphilis is a rare STD nowadays. However, if you have it and it remains untreated it can cause your baby to have abnormalities. It can also cause a still birth in certain cases.

The test done to test for Syphilis is called VDRL test (Venereal Disease Research Laboratory Test) and is fairly accurate at diagnosing the disease.


All pregnant women are offered a blood test to detect AIDS and HIV. If the result is a positive, then steps are taken to minimize the risk of you transmitting the infection to your baby.

Additional tests are offered during the first trimester?

In addition to the above mentioned tests, your doctor may prescribe some additional tests as per requirements.

  • Thyroid Screening
  • Rubella (German Measles)
  • Combined Screening test
  • CMV (Cytomegalovirus)
  • Hepatitis C
  • Herpes Simplex Virus (HSV)
  • Thalassaemia and Sickle Cell Disease
  • Toxoplasmosis
  • Vitamin D Screening

We shall be covering these in our following articles.