About tests in pregnancy

During your pregnancy, your midwife or doctor might recommend tests to check your health and your baby’s health and development. These could be ultrasound, blood, urine and swab tests.

Your midwife or doctor will recommend routine tests that are offered to all pregnant women. You might be offered additional tests if you have certain risk factors or conditions.

The results of these tests help you and your midwife or doctor plan your options for pregnancy care and birth.

Your midwife or doctor needs your permission to do tests in pregnancy. It’s OK to ask them for more information about tests – what they’re for, why you need them, and what could happen if you do or don’t have them.

In pregnancy, you can also have screening and diagnostic tests for chromosomal anomalies and other conditions in your baby. Tests for chromosomal anomalies and other conditions are different from the routine health and development tests described in this article.

Ultrasound scans in pregnancy

You’ll probably have at least 2 ultrasound scans during your pregnancy.

Your midwife or doctor might send you to an ultrasound clinic or a public hospital department for these ultrasound scans. The results will be sent to your midwife or doctor and possibly to you as well.

Routine pregnancy ultrasound scans
You’ll be offered routine pregnancy ultrasound scans in:

• the first trimester at 11-13 weeks
• the second trimester at 18-20 weeks.

Non-routine pregnancy ultrasound scans
In early pregnancy, your midwife or doctor might recommend a non-routine ultrasound scan if:

• You have vaginal bleeding or abdominal pain.
• There’s uncertainty about your pregnancy dates.

Later in pregnancy, your midwife or doctor might recommend extra ultrasounds if:

• There are concerns about your health or your baby’s health and development.
• There were complications in a previous pregnancy.
• You’re expecting twins or multiples.
• Your baby is overdue.

Most ultrasounds show that babies are developing well, but sometimes ultrasounds can pick up on signs of chromosomal anomalies, birth defects, or health or development problems. Some of these aren’t serious and won’t need much, if any, treatment. But some might be more serious. It’s worth thinking about how you might feel if the ultrasound picks up on any concerns or conditions. You and your partner will need support. Your midwife or doctor will be able to help.

Blood tests in pregnancy

Your midwife or doctor will recommend a blood test in early pregnancy to find out your blood type and check for some infections and other health concerns.

These include your rubella immunity, and whether you have anaemia, HIV, hepatitis B, hepatitis C or syphilis. Depending on your results, your health professional will let you know about the best treatment for you in pregnancy or straight after the birth.

Rh type blood test

It’s important to test your blood to find out your blood type and Rh type.

If you’re Rh-negative and your baby turns out to be Rh-positive, this is OK for this baby. But it might cause serious health problems in any babies you have in future.

But no-one knows what your baby’s blood type is until after birth. So if you’re Rh-negative, you’ll be offered an injection called Anti-D at your 26-28 week antenatal appointment and your 34-36 week appointment.

You’ll also be offered Anti-D if you have bleeding during pregnancy. This reduces the risk of health problems for future babies.

After your baby is born, blood is collected from your baby’s umbilical cord and the Rh type is checked. You’ll be offered another Anti-D injection if your baby is Rh-positive.

Gestational diabetes blood test

The blood test for gestational diabetes is usually done at 24-28 weeks of pregnancy. If you’ve had gestational diabetes in a previous pregnancy or you have a high chance of getting this condition, your health professional will probably suggest you have the test at your first antenatal appointment.

The test usually involves a glucose tolerance test (GTT), where you have to fast (not eat or drink) overnight. Your blood is tested, and then you drink 75 g of glucose in a sugary drink. You have your blood tested twice more – after 1 hour and after 2 hours.

If you have high blood sugar levels on a glucose tolerance test, you’ll be diagnosed with gestational diabetes.

Sometimes there are other ways to test for gestational diabetes. Talk to your midwife or doctor about your options.

If you have gestational diabetes, it means you have a complex pregnancy and need additional care and management. Most women with gestational diabetes can have healthy pregnancies and babies when the diabetes is managed well. If it isn’t managed carefully, it can cause serious problems for you and your baby. You might be referred to a specialist pregnancy clinic and diabetes educator.

Urine tests in pregnancy

Some urine infections don’t have symptoms, so a urine test is recommended at your first antenatal appointment to check whether you have an infection.

You might be offered a urine test at other times during pregnancy as well.

The test usually involves you urinating into a small jar. Sometimes you can do this at home and take the jar with your urine sample to your midwife’s or doctor’s consulting rooms. Or you might just do it while you’re at your appointment with the midwife or doctor. Your health professional will tell you exactly what to do and send the sample for testing.

This test is important because if urine infections aren’t treated, they can cause premature labour or low birth weight in your baby.

Urine tests also look at sugar, blood and protein in your urine. These things can be signs of other medical concerns.

Group B streptococcal (GBS) test

Group B streptococci (GBS) are bacteria that often live in the bowel, vagina and anus. They don’t usually cause problems for you. But if the bacteria pass to your baby during birth, this could cause an infection that might make your baby very sick.

There are 2 ways of reducing the chance of your baby getting a GBS infection. Different hospitals or health professionals will recommend one of these ways.

The first way is a screening method called a ‘low vaginal swab’ at about 35-37 weeks. This involves wiping a special stick (called a swab) just inside your vagina and around your anus. You can do this yourself, usually in a bathroom at your midwife’s or doctor’s consulting room. Your midwife or doctor sends the swab away to be tested for GBS.

If you have GBS, you’ll be offered intravenous antibiotics during labour to lower the chance of infection to your baby.

The other way to reduce the chance of your baby getting a GBS infection is to assess you for GBS risk factors without doing the swab in pregnancy. If you have risk factors, you’ll be given intravenous antibiotics in labour. Risk factors include the following:

• Your baby is premature (less than 37 weeks).
• You’ve had a baby with a GBS infection in the past.
• It’s been a long time since your waters broke (usually 18-24 hours).
• You have a high temperature in labour.
• GBS is found in a urine test during pregnancy.

If you have risk factors for GBS or you’ve had a positive GBS result, your midwife or doctor will discuss your treatment options with you before you go into labour.