Antenatal screening

When you’re pregnant, your GP or midwife will recommend antenatal screening. They can take your blood to test for diseases or conditions that could affect your health or your baby’s health. They check your blood count and blood group, and look for rubella immunity, syphilis, hepatitis B and HIV infection.

Agreeing to screening

When you’re between eight and 12 weeks pregnant, you’ll have your first antenatal appointment. The antenatal clinic will take your blood if you agree to screening.

They only need one blood sample for all six tests. You can refuse any of these tests. If you refuse a test, they'll offer you the test later during your pregnancy.

If you want more information about the tests, ask the doctor or midwife at the clinic. The tests and your results are confidential.

Blood count

A blood test indicates your level of red blood cells. This test checks if you have iron deficiency anaemia.  You might need tests to check B12 and folate deficiency anaemia.


If you have iron deficiency anaemia, you might need to take iron tablets. You'll need to improve the iron intake in your diet. If your anaemia doesn't improve, you might need other treatment. The treatment will depend on the type of anaemia and what's causing your anaemia. 

Blood group

This test indicates your blood group. It also shows whether your blood is rhesus negative or positive. This is important if you need a blood transfusion.

If your blood is rhesus negative, you will be offered an anti-D injection by your midwife when you’re between 28 and 30 weeks pregnant. You will need an anti-D injection earlier if you have:  

  • shown signs of possible miscarriage
  • a fall or sudden jolt
  • an injury to your tummy during pregnancy

If you’re rhesus negative, you’ll need an anti-D injection after the birth if your baby is rhesus positive. This protects your next baby from anaemia and jaundice.


This test checks if you’re immune to the rubella virus, also known as German measles. Most adults in Northern Ireland are vaccinated and immune to the virus. If you’re not immune, you should avoid contact with anyone who has rubella when you’re pregnant.

If you come into contact with someone who has the virus, you should tell your doctor immediately. They'll give you a blood test to check if you’re infected.

Congenital rubella syndrome (CRS)

If you become infected with rubella in early pregnancy, your unborn baby could get congenital rubella syndrome (CRS). This can damage their:

  • sight
  • hearing
  • brain
  • heart

If you’re over four months pregnant, rubella is unlikely to affect your baby.

Treatment if you’re not immune to rubella

If you’re infected, you can’t get treatment for rubella when you’re pregnant. Your doctor will offer you two doses of MMR (measles, mumps and rubella vaccine) at least four weeks apart after your baby is born. Vaccination will protect you from infection in future pregnancies.

It’s important you don’t become pregnant for a month after getting the MMR vaccine.


This test checks if you have syphilis, a sexually transmitted infection (STI).

If you’re pregnant and have syphilis, you could pass the infection to your unborn baby during pregnancy or delivery. This is more likely to happen in the early stages of your infection.

How syphilis can affect a baby

Syphilis increases the risk of:

  • miscarriage
  • stillbirth
  • premature birth

If you’re infected with syphilis, there is an increased risk your baby will have congenital syphilis, a lifelong illness.

Treating syphilis during pregnancy

If your syphilis test is positive, a specialist doctor will prescribe antibiotics. Taking these won’t harm your unborn baby. The doctor will check your blood after treatment to make sure the infection has gone. By treating syphilis early, there is less risk of permanent damage to your health and your baby’s health.

  • Syphilis

When your baby is born, a doctor will take their blood and check for signs of congenital syphilis. The doctor will give your baby antibiotics if necessary.  

Hepatitis B

Hepatitis B is a virus that can cause liver disease. It can be transmitted:

  • through close sexual contact
  • through injecting drugs
  • through contact with infected blood
  • from mother to baby during pregnancy

If you have the virus or become infected during pregnancy, your baby is at risk of developing congenital hepatitis B. This is a long-term condition that can lead to liver disease.

Treating hepatitis B

If screening indicates you have hepatitis B, you'll need to see a liver specialist during pregnancy. They might prescribe antiviral drugs to take later in pregnancy. When your baby is born, they will get a hepatitis B vaccine to reduce their risk of becoming infected.

Vaccinating against hepatitis B infection

Your baby will need a hepatitis B vaccine when they’re:

  • newborn
  • one month old
  • two months old
  • a year old


This test detects the virus that can cause AIDS. If you’re infected with HIV, you could pass the infection to your baby during:

  • pregnancy
  • childbirth
  • breastfeeding

How HIV can affect your health

HIV damages your immune system. Without treatment, your weakened immune system can’t fight infection. Eventually you could develop AIDS.

Treating HIV

If you’re HIV positive and pregnant, your medical consultant will prescribe antiretroviral drugs. Taking these won’t harm your unborn baby. This treatment helps protect your health and reduces the risk of your baby becoming infected.

After the birth , your baby will also require treatment with antiretroviral drugs and a blood test to see if they are infected with HIV.

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