The test that reveals to a couple that they are going to become parents is just the first of a considerable number of tests that expectant Mums will be offered over the next nine months. Some are very simple and easy to understand – the ultrasounds that visually check the baby’s development, the basic blood and urine test that help monitor the health of both Mum and Baby. Other tests are a little more complicated though and some women may not even choose to undergo them. One of the decisions that couples sometimes struggle with in this regard is whether or not they should choose to have their developing baby screened for Down’s Syndrome.
What is Down’s Syndrome?
Down’s Syndrome is the name that covers a set of varying physical and mental problems that are the result of the presence of an extra chromosome – Chromosome 21. This is also often referred to as Trisomy 21 as there are 3 of these chromosomes present instead of the usual two.
Although people with Down’s Syndrome have some mental and physical features in common the condition can range from rather mild to sever enough to cause premature death. advances in the understanding of the syndrome and the importance of early intervention have meant however that many children who are born with Down’s Syndrome, although they will never be cured, are now leading longer, fuller lives than ever before.
What Causes Down’s Syndrome ?
Exactly why chromosomes may develop abnormally resulting in Down’s Syndrome is something scientists are still trying to figure out. Anyone can conceive a baby that has the chromosomal abnormality but statistically the older the Mum at conception the higher the odds of such an occurrence, especially in women over 35.
Who Should be Screened?
These days women over the age of 35 are routinely advised to undergo Down’s Syndrome testing as a precaution. Those with a history of a number of unexplained miscarriages are also often advised to undergo chromosomal screening as many of the fetuses that develop with an abnormality do not survive, resulting in a miscarriage. If either parent has a history of chromosomal abnormality in their immediate families they are also usually advised to consider testing as well.
This however is a personal decision for an expectant couple to make as the issues are more complicated than it may seem at first.
How Down’s Syndrome Screening Works
Basic Down’s Syndrome screening, which involves blood tests and ultrasounds, will not tell a couple for sure whether or not their baby has Down’s Syndrome but provide a statistical probability that they might – based on the test results and other factors like age and previous pregnancies. Couples will usually be given their result in the form of a number as was as a “normal” or “abnormal” label.
These basic screening tests alone are not a guarantee that a baby does or does not have Down’s Syndrome, in fact some abnormal screening results of this kind are inaccurate and the baby is fine. On the other hand some “normal” test results turn out to be inaccurate as well so even after the basic Down’s Syndrome screen some higher risk mothers are advised to consider more invasive tests.
These tests, most commonly known as amniocentesis or chorionic villus sampling (CVS) can determine with 99% accuracy whether or not a baby has Downs Syndrome or other chromosomal abnormalities. Because this involves taking samples from the amniotic fluid itself the test does carry with it a small risk of miscarriage.
The Pros and Cons of Down’s Syndrome Testing
Down’s Syndrome testing has also advanced with the increased general knowledge about the disease and can now be carried out in the first trimester of pregnancy as well as the second and is considered to be reasonably safe for the baby. The small risk of miscarriage is one that some couples do not want to take at all though.
Other couples have a more cerebral objection to the idea of Down’s Syndrome testing. They simply would not want to know if such an abnormality existed because of all the moral dilemmas that then come into play if the results are positive.
These days a growing number of obstetricians will suggest that higher risk women meet with a genetic counsellor if they are unsure about Down’s Syndrome testing so that they can gain a better understanding of the issues from a medical and emotional point of view before making a decision.
There really is no right or wrong answer to the question of whether or not an expectant couple should opt to undergo Down’s Syndrome screening when pregnant. Like so many other aspects it is a very personal decision, but it is one that should be made with the input of your OB or midwife.
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