Early in your pregnancy your doctor will ask if you want to test for Down Syndrome. Most couples do choose to do the test, but it is optional.

Down Syndrome is also called Trisomy 21 and occurs when the baby inherits 3 copies of chromosome 21 instead of the usual 2 copies.  This results in a variety of features including particular facial features, intellectual disability and sometime heart defects amongst other things.  A person with Down Syndrome will need care and support for their whole life.

The chance of any woman having a baby with Down Syndrome is 1:667.  The chance is greater in older women and may be as high as 1:100 in women aged 40.

There are 3 basic options for testing your individual risk, taking into account your age as well as ultrasound and/or blood results:

1) First trimester screening

This is a blood test for hormone levels PLUS an ultrasound measuring the thickness of the baby’s nuchal (neck) membrane. The blood test is done between week 10 and week 14. The scan is done between week 11 and 14.

2) Non-Invasive Prenatal Testing

This is a blood test only which looks for and tests baby’s DNA which is floating around in your blood stream. NIPT can be done after 10 weeks.

3) Maternal serum screening.

This is a blood test only for hormone levels.  It is done around week 16.

Each of the above tests has its own benefits. Usually only 1 test is needed.  They are screening tests and the result will be given as “low risk” or “high risk”.  If the result is “high risk” then your doctor will discuss further testing to determine for certain whether or not the baby has Down Syndrome.

If your baby does have Down Syndrome, or another medical issue is identified, you may choose to continue your pregnancy or not.

Remember that no test can test for “everything” and that you should always talk to your doctor about your options.

This article has been written by Dr Elizabeth Tompkins