Antenatal Test

What is an Antenatal Test?

Antenatal tests (or prenatal tests) are assessments designed to protect the health of pregnant women and their babies throughout pregnancy. Though there are various tests that serve different purposes, these are all important prenatal procedures for determining risk factors for certain conditions or birth defects, as well as monitoring fetal growth, and the health of the mother.

The three types of antenatal tests that one can expect are blood tests, urine tests, and ultrasound scan tests. Different tests are completed throughout pregnancy, with some being first-trimester screening tests, and others completed in the later weeks of pregnancy. Though all of the tests are important, only some of them are recommended for all pregnancies, as these serve as screening tests to detect any risks to the woman or baby's health.

Additional testing is typically recommended upon referral following screening results, or for women who have a family history of medical problems or genetic disorders. In this instance, health practitioners may recommend further diagnostic testing to determine whether the unborn baby may experience health problems in the future. These may include Chorionic Villus Sampling (CVS) in response to high risks of chromosomal abnormalities for Down's syndrome.

It can be understandably overwhelming to navigate these tests during pregnancy, given that all the tests have different procedures or results associated with them. To help support healthcare practitioners and women during pregnancy, we have developed an Antenatal Test resource. This resource outlines all of the tests that may be available from early stages at the first antenatal visit, to recommended tests for the later weeks of pregnancy.

Using this resource can also help health practitioners devise an effective prenatal care plan, structuring each antenatal visit with relevant screening test procedures, test results, and tailored advice to support the individual.

Types of Antenatal Tests

Blood tests

Prenatal blood tests are screening procedures that are typically conducted at a blood pathology site, where a small blood sample is extracted from the pregnant individual, before it is taken to a laboratory for testing. These tests typically begin at the first antenatal visit, where the blood sample is used to assess the following:

• Full blood count
• Blood group and antibody identification
• Diabetes screening
• Screening for infectious diseases
• Levels of vitamin D

However, a pregnant individual may have several blood tests throughout pregnancy to continue assessing their health, such as the iron levels and risk for diabetes, as well as conduct further screenings for the following:

• Non-invasive prenatal testing (NIPT)
• Gestational diabetes screen

Urine sample test

This test is usually conducted at the first antenatal visit, but may be repeated throughout pregnancy to test for any bacteria or infections. The procedure involves the pregnant individual providing a urine sample, which is then taken to the lab to complete a urine culture test.

Ultrasound scan

An ultrasound scan is a screening test that is conducted throughout pregnancy. One of the first ultrasound scans is conducted in early pregnancy to conduct a dating scan to predict the due date. In later stages of pregnancy, usually between weeks 18 and 20, a morphology scan is usually completed to assess the growth and development of the fetus.

However, ultrasound scans are also used for screening procedures to estimate the risks of a the child having developmental or genetic conditions, using the following tests:

• Nuchal translucency test
• Combined first-trimester screening (CFTS)

Procedural tests

Procedural tests during pregnancy are special tests that use their own procedures. The two most common tests of this type are:

• Chorionic villus sampling (CVS) test
• Amniocentesis test

Both of these are diagnostic tests that screen for genetic or chromosomal disorders, such as Down's syndrome and open neural tube defects. These are recommended following the prenatal screening results of the nuchal translucency test or CFTS, which may have identified potential fetal abnormalities or risks of chromosomal abnormalities. Additionally, these may be recommended for individuals who have a family history of genetic disorders, but require further diagnostic testing.

Vaginal-swab test

The vaginal-swab test is a diagnostic test for any infections or bacteria that may propose any health problem to the pregnant individual, or harm to the baby's health.

How does an Antenatal Test work?

Antenatal testing can look different between women, as some individuals may have an increased risk of having children with chromosomal abnormalities or health conditions that lead to serious illness.

By understanding which prenatal screening tests are required during pregnancy, health practitioners can proactively assess the health status of the individual and their unborn baby. Using our free Antenatal Test resource offers efficient assessment for diagnoses of patient illness or genetic abnormalities, which can support proactive prenatal care.

Step 1: Consultation

In the first antenatal visit, present our Antenatal Test resource to the individual. Take care to explain the various test types, and the purpose of prenatal testing. It may also be beneficial to explain the timeline of trimester screening tests, and incorporate these into the individual's prenatal care plan.

Crucially, take time to explain that the decision to complete any antenatal screening and diagnostic tests is completely up to the choice of the pregnant individual. Should they choose to not complete a test, or additional testing after the first trimester, it is critical to provide ongoing support and care.

Step 2: Patient information

Prior to any testing procedures, ask patients to complete the patient information section. This includes their lead maternity care provider, current health status, any symptoms, and family medical history. Having this information can help identify which tests may be required.

Step 3: Conduct testing procedures

Depending on the stage of pregnancy, testing procedures will look slightly different at each antenatal visit. The resource provides information about what each test is for, and when it should be conducted to help you plan your prenatal care visits.

Understanding test results

Results following antenatal testing are multifaceted, in that individual results can differ greatly amongst pregnant individuals. These are usually dependant on a number of factors, including family history, the stage of pregnancy, and genetic material. Understanding test results is critical to informing effective prenatal care.

The following are some common results experienced from both screening tests and diagnostic tests, and what they may mean for an individual:

• Normal results: Following screening tests, some expectant mothers may receive normal results that indicate healthy fetal growth and a safe pregnancy. In this instance, health care practitioners may continue with the initial prenatal care plan, scheduling antenatal visits to continue documenting the progression of the pregnancy, assessing the mother and baby's health.
• Uncertain results: Some results may be uncertain or inconclusive, and require further screening tests or diagnostics to determine the true result.
• Abnormal results: Individuals may also receive abnormal screening test results, such as low iron levels following a blood test or increased risk of genetic defect. If this is the case, health professionals may recommend a diagnostic test after the first trimester to gain further information.

If a diagnostic test returns an abnormal result, it is essential to begin care planning. In particular, persistent symptoms or conditions such as low blood glucose or infection require immediate treatment to protect the health of the expectant mother and fetus.

If genetic diagnostic procedures return positive for genetic abnormalities, health practitioners may recommend genetic counseling to expecting parents. The genetic counselor can provide information and support, discussing the results and what this may mean for the child's health and well being.

Why is testing during pregnancy important?

Antenatal testing is primarily designed to gain insight about the baby's health, and help practitioners devise effective prenatal care plans to support pregnant women. Completing an antenatal test can support:

• Early detection of medical problems that may harm the expecting mother or child, such as infection or illness. This can prompt treatment to nurse them back to health.
• Early identification of any genetic conditions the child may be born with, such as spina bifida or Down's Syndrome. This can allow for early planning with a genetic counselor to develop plans or strategies to support the child following birth.
• Assessing the baby's health and development throughout the pregnancy. By completing procedures like fetal heart rate monitoring and fetal blood tests, health practitioners can monitor fetal growth and detect any issues. This can help mitigate risks of pregnancy loss or complications.
• Provides information and reassurance for high-risk pregnancies. These may include individuals who are over the age of 35, have a family history of genetic conditions, or are experiencing any complications throughout pregnancy.

Although antenatal test results can provide important information and have many benefits, it is ultimately up to the choice of the pregnant individual. If you have any concerns or are wondering if prenatal screening is for you, it would be greatly beneficial to contact your primary health care provider, lead maternity care provider, or genetic counselor.

References

John Hopkins Medicine (n.d.). Common Tests During Pregnancy. Wellness and Prevention. https://www.hopkinsmedicine.org/health/wellness-and-prevention/common-tests-during-pregnancy

Ministry of Health (2016). Antenatal Blood Tests. National Screening Unit, New Zealand Government. https://www.nsu.govt.nz/system/files/resources/antenatalbloodtests19jan16.pdf