These blood tests are important for your health 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.
All pregnant women are also offered screening for infectious diseases during pregnancy.
How much blood is taken
You will give only a small amount of blood during the test. This will be taken once, using one needle. This sample of blood will be tested for a variety of viruses. The process is simple and trouble-free for most people.
Fear of needles
Tell the person who is taking the blood if you are afraid of needles. They deal with this issue often. They can help to make the experience easier for you.
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.
Anaemia can cause you to become very tired. Other symptoms include breathlessness and feeling faint. You may look 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. Eating foods rich in iron may help.
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.
Blood group and antibodies
You will have your blood group and antibodies tested. The most important antibody tested is the Rhesus (Rh) Factor.
Rhesus (Rh) Factor
Rhesus factor is an inherited protein found on the surface of red blood cells. If your blood has the protein, you are Rhesus positive. If your blood lacks the protein, you are rhesus negative.
If you are rhesus negative, there is a risk your body could produce antibodies against Rhesus. This might affect future pregnancies. It could also cause anaemia and jaundice in your baby. You may be offered injections during your pregnancy to prevent this.
Anti-D injections stop rhesus negative women from producing these antibodies.
If you are rhesus negative, you may be offered anti-D injections at 28 weeks. You may also be offered the injection after the birth. This injection is safe for you and your baby.
You may also be offered anti-D earlier on in your pregnancy if you have an injury to your tummy, or a bleed.
Other blood tests offered during pregnancy
You may have more blood tests done. These can be due to medical problems you have, or your family history. Extra tests are also done based on your ethnic background or occupation.
Some of the other blood tests offered to pregnant women are listed below.
Oral glucose tolerance test
An oral glucose tolerance test (OGTT) will check if you have gestational diabetes. This is a type of diabetes that can develop in pregnancy. Some maternity hospitals give all pregnant women the test. Other hospitals will only test you if they feel you are at a high risk of developing diabetes.
Diabetes in pregnancy can cause complications for you and for your baby. But the risk is usually lower if the diabetes is detected early and managed well.
You will need to fast the night before the blood test. You can usually drink water, but you will need to check with the hospital. After the test, you will get a glucose drink. You will have 2 more blood samples taken. These will happen 1 hour and 2 hours after you have the glucose drink.
Sickle cell disease and thalassaemia screening
Sickle cell disease and thalassaemia are conditions that people inherit. They can affect the way oxygen moves around the body.
You may get a test if you are of African or Mediterranean origin. 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 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.
Immunity to parvovirus
Parvovirus is also known as 'slapped cheek disease'. You can get tested to see if you are immune to parvovirus. You may need to get tested if you are in contact with a person who has the virus.
If you are immune to parvovirus, then you should have no concerns. If you have the infection, your pregnancy will be watched closely. You may also need extra ultrasound scans.
Thyroid function test
Blood tests will be familiar to you 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.
You may need regular tests during pregnancy. You may also need to see an endocrinologist.