Chromosomal Abnormality Screening

Genetic abnormalities like Down syndrome affect about one in every 700 babies. The risk of having a child with Down syndrome does increase with maternal age, but mothers of all ages and races can have a child with Down syndrome.

A child with Down syndrome is born with an extra copy of chromosome 21, causing delays in their mental and physical development.

The recommendation is for all pregnant women to screen for foetal chromosomal abnormalities, regardless of their age. Non-invasive options for screening include:

• Ultrasound scan (Nuchal translucency scan) in combination with a maternal blood test
• Non-Invasive Prenatal Test (NIPT) that allows isolation of baby’s cell from maternal blood

The Nuchal translucency scan is recommended even if you decide to have the NIPT, as the ultrasound scan can detect other abnormalities that will not be detected with the NIPT.

If an abnormality is suspected, then your obstetrician will recommend an invasive diagnostic test for confirmation.  This may involve a chorionic villus sampling (CVS) or amniocentesis, where a needle is passed through the mother’s abdominal wall, into the placenta (for CVS) or the amniotic sac (for amniocentesis), to obtain cells directly from the baby for testing.