Approximately 12 weeks
This ultrasound scan is performed at around 12 weeks into the pregnancy (between 11 weeks and 4 days and 13 weeks and 6 days).
In 95% of foetuses, the nuchal fold (an area of tissue at the back of an unborn baby's neck) is thin and the associated risk of chromosomal abnormalities is low.
A thickened nuchal fold, however, is observed in 5% of the foetuses. This group has a higher risk of chromosomal and other abnormalities.
At birth, the majority of foetuses with a thickened nuchal fold do not appear to have abnormalities. In addition, normal ultrasound imaging cannot always exclude a chromosomal abnormality (e.g. Down syndrome).
So, what does this test tell you? A higher risk calculation only indicates that further investigation may be required. You will want to talk to your doctor about how to interpret the results before deciding to proceed with more diagnostic testing.
This test is eligible for reimbursement by your health insurance.