Prenatal Testing

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Prenatal Testing

There is an important distinction to be made between screening tests, which determine the likelihood or risk of a baby having a condition, and diagnostic tests which will give a definitive answer. Some screening tests will produce results which mean an invasive test will be necessary if the parents want a diagnosis. In order to make an informed decision about whether or not to have these tests, it is important to explore the implications of both positive and negative test results. Reflecting upon your reasons for testing and what course of action you might take if the results are positive, is part of this decision making process.

In the early months of your pregnancy, you will be offered the opportunity to engage with screening and diagnostic tests which will provide you with information about the health of your baby.

The meanings of screening and diagnosis are different but they are often confused. Screening involves determining the risks or likelihood of a condition, whereas a diagnostic test will give a definite answer. Sometimes the results of a screening test might suggest the need for an invasive test in order to obtain a diagnosis, for example an amniocentesis for Down syndrome.

Before you decide to test and even which test(s) to have, it is worth considering what the benefits are for you in testing so that you can weigh them up against the risks. You may also want to consider what you might do with the information the results might provide.

You might wish to ask yourself what the reason is for wanting to know if your baby has a health condition.

Do you want to be able to prepare emotionally for your baby’s birth?

Only 2% of all full-term births produce babies with some form of congenital anomaly.

Some parents want the information in order to be able to make decisions about whether to continue with the pregnancy and if they do, how to prepare themselves both emotionally and practically for parenting a child with a disability.

The psychological impact on parents of being told and/or shown that their baby has a congenital abnormality is often not dissimilar to the grieving process involved in the loss of a child through miscarriage, stillbirth or neonatal death.

Do you want to arrange for treatment during pregnancy or immediately after the birth if necessary?

Some conditions may require intra-uterine surgery or referral to a hospital containing a neonatal surgery unit specializing in a particular condition. You may wish to consider your options for where to have your baby so that you can be near these specialised facilities.

Do you have a personal or family history of congenital anomaly and need reassurance that your baby is not suffering from that condition?

Some abnormalities are slight and cause no further problems for the parents or child, while others are profound and will impact on daily life.

Do you want to arrange for a diagnostic test if a screening test indicates that your baby is at risk of having a specific condition?

If a screening testing indicates that your baby is at higher risk of having a specific conditions, the diagnostic tests Chorionic Villus Sampling (CVS) and Amniocentesis will provide you with a firm diagnosis.

Do you want to have the option of aborting a pregnancy which is confirmed as having a congenital abnormality?

Parents who decide to abort an abnormal fetus, believe that life lived with the disability will not have sufficient quality, or that they as parents are unwilling to provide the long-term support that a child with a disability may require.

Risks of Prenatal Screening and Diagnostic Tests

  • Prenatal screening will only provide you with an expressed ratio of how likely the fetus is to have a certain condition.
  • Screening tests can raise parents' anxiety levels and thoughts of abnormalities can remain in parents’ minds until the baby is born, even if results are negative.
  • Some screening tests are adequately discussed with parents beforehand, for example the Maternal serum screening, but others, like ultrasound are not presented in the same way. Ultrasound can be both a screening and diagnositc test, providing even more definitive information regarding abnormalities.
  • There is often a long wait for the results of some of the diagnostic tests and this has been described by women as the worst factor of it. During this time parents often feel ‘in limbo’, perhaps denying their pregnancy, refusing to become too attached to the baby.
  • False positive test results where a baby is diagnosed with having a condition and is subsequently found not to have it, or the condition is less severe than indicated, do occur.
  • A positive test result can have an impact on a parent’s ability to bond with their child, even when after birth it is revealed that the baby is normal and the test result was a false positive. The test result can still stand in the way of the parent accepting the normality of their child.






Screening tests


determine the risk or likelihood of a condition.







Diagnostic tests


give a definite answer.







Question yourself


Reflecting upon your reasons for testing and what course of action you might take if your baby is diagnosed with an abnormality, will help you to make an informed decision about whether to test and what tests to have.