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Downs Syndrome Screening and Tests

The first time many of us encounter Downs Syndrome is during our first pregnancy. Flushed with the joys and excitement of discovering you are pregnant you are given an appointment to see a midwife. Amongst other things such as checking the health of your baby, you will be offered a number of tests. Most people, like me, go into these tests without a second thought, but if you are here reading this page, you've presumably have a reason to find out more.

Antenatal testing is a very emotive topic. I believe parents should be given full and frank information to allow them to make their own decisions. I hope this page (and the rest of this site) will help you if you are having to make what can be unquestionably very difficult decisions. If you are wildly pro or anti abortion, these pages aren't for you!

What you want to know will depend on why you are asking so here are some common questions.


Why have tests at all?

The simple answer is because people want them. Most parents long for a normal child and many parents do choose to terminate pregnancies for hundreds of reasons. Others are just seeking to find out as much as they can about their unborn child (in the same way as they have regular scans) to help them prepare for and bond with their unborn child.

Before taking any tests, it's important to understand that Downs Syndrome is a condition which starts at conception. If you are already pregnant and your foetus has Downs Syndrome, that is an unchangeable fact. None of the tests can make your foetus not have Downs Syndrome and neither can having tests cause Downs Syndrome. At the end of the day, if the tests show that your foetus already does have Downs Syndrome you will have two choices, to continue the pregnancy or to terminate the pregnancy. There is no cure. There is no easy answer. It won't just go away. This can be a hard thing to accept in our society where we are used to taking things back if they are "broken" and being handed an immediate replacement that's "fixed". That's not an option with babies.

Too many parents find themselves a long way down the testing path before finding they are being asked to make heartbreaking decisions they are not prepared for. Often they're asked to make decisions while they're under huge pressure and in a very short time window. Before you start, it is well worth looking at what matters to you, finding out about Downs Syndrome and discussing your values with your partner while things are relaxed and calm.

For more information about tests in the UK, see the NHS leaflet "Testing for Downs Syndrome in Pregnancy"


I've just found out I'm pregnant; so what are these tests I'm being offered?

The first tests you are offered are screening test. The tests won't say for definite whether your foetus has Downs Syndrome, but will give you a risk. For example if you are told your risk is 1 in 200, that means that if you took 200 babies with a similar result, one of them would have Downs Syndrome. 1 in 2 means that half of them would. 1 in 2000 sounds better, but doesn't mean your baby definitely won't have Downs Syndrome; if you took 2000 babies with that result, one would probably have it. The higher the second number, the lower the risk.

You will usually be offered (but are under no obligation to have) a blood test to check for the possibility of Downs Syndrome between 10 to 14 weeks. During a blood test, a sample of your blood will be taken and tested to check the levels of certain proteins and hormones. This is also called Biochemical Serum Screening. If your blood contains abnormal levels of these substances, you may have an increased risk of having a baby with Down's syndrome.

You may also be offered a special type of ultrasound, known as a nuchal translucency. This type of ultrasound works in the same way as a normal ultrasound scan, but it focuses on measuring the space between the spine and the nape of the baby's neck. All babies tend to collect fluid behind the neck. However, babies with Down's syndrome normally have more fluid in the neck than is normal. By measuring the thickness of fluid, your doctor can help to determine how likely it is that you will have a baby with Down's syndrome.

Sometimes these tests are taken together and referred to as a combined test. The midwife will collect together all the results and give you a risk ractor.

It is important to discuss whether you really want to have the tests at all. If these initial screening tests come back indicating a high risk of Downs Syndrome, you have only two options:- to go on to have a diagnostic test with an increased chance of miscarriage or doing nothing but have to continue your pregnancy knowing you are at high risk. If you are not happy with either of these options you may be better off not having any tests in the first place.


I've just been told there's a risk that my baby might have Downs Syndrome; what happens next?

If your screening test came back with a risk of 1 in 250 or higher then you will be offered further diagnostic tests. The earlier screening tests only give a risk, diagnostic tests come back with an absolute yes/no answer. There are two diagnostic tests available - chorionic villus sampling (CVS) is performed from 11 to 14 weeks, and amniocentesis is performed from 16 weeks of pregnancy.

Before getting into diagnostic tests it's vitally important to openly discuss whether or not to have the diagnostic tests and what you are going to do if the test comes back positive. By the time the test comes back you may well be very obviously pregnant.

It is also important to discuss the risks associated with the tests. While screening is effectively risk free, the diagnostic tests both carry a risk of miscarriage which may be higher than the risk of your baby having Downs Syndrome.


I've just had the results of my amnio/CVS and the results are positive; what does this mean?

This means that your baby definitely has Downs Syndrome. You now have three choices: to continue the pregnancy and bring the baby into your family, to continue the pregnancy and have have the baby adopted or to terminate. All the leaflets tend to start to gloss over things at this point, probably because there's no getting away from the fact that there is no "make it all OK" option and none of the options are particularly attractive to most people.

Hopefully you have thought about all this in advance but most of us don't! Do take time now to find out as much about Downs Syndrome as you can before making a decision by doing things such as looking at this site (note that Freddie has far more complex issues that most children with Downs Syndrome so isn't your best benchmark!). I am still rather haunted by an article I read in a newspaper by a journalist who had had a late termination after a positive diagnosis. She listed a whole load of things she wanted her daughter to be able to do and had terminated because "it could never be". She'd hated the termination and was obviously deeply unhappy. I looked at her list and couldn't think of one thing she wanted that the girls I know with Downs Syndrome wouldn't have been able to do and enjoy. I always wonder how she'd feel if she met them and find that they didn't live up to her very poor stereotype.

You may look at it all and genuinely decide that having a child with Downs Syndrome is something you don't think you can do whatever the cost. But if you do make that decision, make it on up to date information, not based on stereotypes or how things were 20 or more years ago.