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Blood tests offered in pregnancy

During your pregnancy, you'll be offered blood tests.

This is part of free public antenatal care.

These blood tests are important for you and your baby's health. They test for a wide range of conditions.

Talk to your GP or midwife if you have any questions about these blood tests.

You will also be offered screening for infectious diseases.

Having a blood test in pregnancy

You will give a small amount of blood during the test. This will be taken once, using 1 needle. This sample of blood will be tested for different viruses. The process is simple and trouble-free for most people.

If you're worried about needles

Tell the person who is taking your blood if you feel:

  • nervous about needles and blood
  • dizzy and faint during or after your test or if this has happened to you before

They can try to make you feel more comfortable. For example, by letting you lie down for the test.

Types of blood tests in pregnancy

You will be offered a blood test to find out your full blood count, blood group and rhesus status.

Full blood count test for anaemia

This test checks for anaemia. Anaemia means that you have fewer red blood cells than normal or that your haemoglobin is low. Haemoglobin is a protein in your blood that carries oxygen. Lack of iron is the most common cause of anaemia in pregnancy.

Symptoms of anaemia can include:

  • being very tired
  • breathlessness
  • feeling faint
  • looking pale

Less common symptoms of anaemia include heart palpitations and ringing in your ears.

If your iron levels are low, your GP, obstetrician or midwife may tell you to take iron supplements. It may help to eat foods rich in iron.

You should also take foods and drinks with high levels of vitamin C. Vitamin C helps your body absorb iron. Avoid drinking tea at mealtimes as this can prevent your body from absorbing the iron in your food.

Iron deficiency anaemia

Healthy eating during pregnancy

Rhesus (Rh) factor

This test tells you whether your blood has the rhesus factor protein. This is the most important antibody test.

If your blood has the protein, you are rhesus positive. If your blood does not have the protein, you are rhesus negative.

If you are rhesus negative and pregnant, your body may produce antibodies against the rhesus protein. This might affect future pregnancies. It can also cause anaemia and jaundice in your baby.

If you are rhesus negative, you may be offered anti-D injections during your pregnancy to prevent this. These injections will stop you from producing these antibodies.

You may be offered anti-D injections:

  • at 28 weeks
  • after your baby's birth
  • early on in your pregnancy if you have injury to your tummy or a bleed

This injection is safe for you and your baby.

Some hospitals can check if your baby is rhesus negative. If your baby is rhesus negative, you do not need anti-D injections.

Other blood tests offered during pregnancy

You may have more blood tests done.

This can be because of:

  • medical conditions you have
  • your family history
  • your ethnic background
  • your occupation

Oral glucose tolerance test

An oral glucose tolerance test (OGTT) checks if you have gestational diabetes. This is a type of diabetes that can happen in pregnancy. It can cause complications for you and your baby unless it is detected early and managed well.

Some maternity hospitals give all pregnant women this test. Other hospitals only test you if they feel you are at a high risk of getting diabetes.

For this test, you will need to fast the night before. You can usually drink water, but check with your hospital.

After this test, you will:

  • get a glucose drink
  • have 2 more blood samples taken - 1 and 2 hours after you have the glucose drink

The test is usually done in the second trimester (usually between 24 to 28 weeks). It takes about 2 hours.

Sickle cell disease and thalassaemia screening

Sickle cell disease and thalassaemia are conditions that people inherit. They can affect the way oxygen moves around your body.

You may get this test if:

  • you are a carrier of the gene that causes these conditions
  • you or your family come from parts of the world where these conditions are more common

Parts of the world where these conditions are more common include:

  • the Mediterranean
  • Africa
  • the Caribbean
  • India
  • Pakistan
  • other parts of Asia

Tell your midwife or obstetrician if you or your baby's father have an ancestor who was born outside northern Europe.

Healthy people can carry the gene for sickle cell disease and thalassaemia. They can pass them on to their children without knowing.

If you are a carrier, you may need more tests. These tests will check if your baby is likely to have one of these conditions.

Thyroid function test

You will be familiar with blood tests if you have thyroid gland problems. These tests may become more regular during pregnancy. This is because your thyroid function could affect your baby.

You can reduce this risk with treatment. If you are on medicine already, your GP, obstetrician or endocrinologist may need to adjust the dose.

Page last reviewed: 22 December 2023
Next review due: 22 December 2026