Antenatal Tests and Investigations
Throughout pregnancy many tests, scans and other investegations are performed. Below is a brief description of the most common tests and some of the reasons they are done.
Every pregnancy is unique and you may be recommended to have other investigations through the pregnancy, depending on your circumstances. If you have questions about tests of investigations that are recommended to you, please don’t hesitate to ask your midwife or doctor.
Dating Scan – This ultrasound is usually the earliest investigation, and confirms pregnancy. A heartbeat is typically detectable between 6 and 8 weeks. This scan is optional and not everyone will have it.
Non Invasive Prenatal Screening – a very accurate test for specific genetic and chromosomal disorders. Also reports on the sex of the baby. Be sure to tell your midwife or doctor if you do not want to know the sex so that extra care can be taken with the information. This is an optional test and isn’t covered by Medicare.
Nuchal Translucency Assessment – a combination of ultrasound and blood testing for the early diagnosis of congenital abnormalities and chromosomal disorders. Whilst many couples choose to have this test, it is also optional.
These tests are usually arranged by your GP prior to booking in to the hospital. The midwife will go over the results with you and ensure all the relevant tests have been done.
Full Blood Count - A complete count of the concentration of cells in the blood. Of particular interest in pregnancy is haemoglobin (cells that carry oxygen), platelets (for clotting). If you have low haemoglobin, you may be recommended to take iron supplements.
Blood Group and Antibody screen – If you have a negative blood group you will be offered and recommended to have prophylactic anti-D. Your midwife will discuss this with you if it applies to you. The presence of antibodies in your blood may indicate the need for further testing or monitoring for your baby.
Vitamin D – Necessary for the growth and development of bones. If you have low Vitamin D you may require supplementation.
Rubella Serology – If you have a low immunity to rubella (German measles), you will need to be careful to avoid exposure during your pregnancy. You will be offered a booster vaccination after your baby is born.
Varicella Serology – If you have a low immunity to varicella (chickenpox) you will need to be careful to avoid exposure during your pregnancy.
Hep B surface antigen – Tests for a current acute or chronic hepatitis B infection. In the instance of an infection, babies are offered additional protection after birth.
Hep C screening – Tests for a current or chronic hepatitis C infection. If positive, additional precautions are taken to protect the baby.
HIV Serology – Tests for HIV virus. If positive, additional planning and precautions to protect baby will be undertaken.
Syphilis Screening – Testing for syphilis infection. If positive, treatment is considered and further testing to assess need for additional protection for the baby.
Chlamydia screening – Women in ‘at risk’ categories will be offered testing for Chlamydia. Chlamydia infection in pregnancy can lead to the baby contracting an infection, and may cause premature rupture of membranes.
Urine culture and microscopy – Testing for urinary tract infection (UTI). A UTI can trigger premature labour if left untreated.
Glucose Tolerance Test (GTT) – if you have a high risk for developing gestational diabetes (due to a family history or ethnicity) you will be offered an early GTT to test of diabetes in early pregnancy in addition to the routine GTT at 28 weeks.
Haemoglobin Electrophoresis – Women of ethnicities at risk of carrying thalassemia will be offered Haemoglobin Electrophoresis if an abnormal full blood count result indicates further investigation.
Morphology Scan – This ultrasound examination assesses the number of foetuses, the anatomical structures, the size of the baby, the position of the placenta, the amount of amniotic fluid around the baby, and the cervix. If anything is abnormal or not able to be assessed, further investigation may be recommended.
Full Blood Count – the full blood count is repeated to check for changes since the earlier test.
Blood Group and Antibody screen – this is repeated to check for the presence of antibodies that may have appeared since the earlier test.
Glucose Tolerance Test – routinely offered to all women to test for gestational diabetes. May be a repeat test if already done earlier in pregnancy.
Vitamin D – if your vitamin D was low earlier in pregnancy, this test is repeated to determine if supplementation has been adequate.
Third Trimester Ultrasound – while this test isn’t routine, if your placenta was close to your cervix at the morphology scan, or there have been other indications, you may be recommended to have an ultrasound in your third trimester, often around 34 weeks.
Group B streptococcus screening – This test looks for the presence of group b streptococcus bacteria in your vagina. Women who test positive will be offered antibiotics in labour to protect the baby from infection.
At each appointment your midwife or doctor will conduct several assessments:
Blood Pressure – if your blood pressure is rising, it may be a sign of preeclampsia or gestational hypertension. Further monitoring and investigation will be recommended.
Fundal Height – assessment of overall fetal growth by measuring your abdomen.
Fetal Position – assessing your baby’s position helps to find the heart rate and in the later stages of pregnancy plan a safe birth.
Fetal Heart Rate and movements – The midwife or doctor will listen to your baby’s heart rate at each antenatal appointment after 16 weeks of pregnancy. This, as well as the baby’s movements, are signs of a healthy baby.