Neck fold is actually a kind of fluid accumulation under the skin. This is at the back of the baby’s neck. All babies have a neck fold. The difference, however, is that some on average have more fluid in the neck fold. This may indicate Down’s syndrome.
This is a measure of the size of the fluid accumulation of the neck fold. The result is only a probability calculation. An amniocentesis or chorionic villus test can definitively prove whether the baby is burdened with Down syndrome. In principle, therefore, it is a preliminary stage for further research if there is an increased chance. You are of course free to decide whether or not to take any further steps. Often the neck fold measurement is part of a so-called combination test, or a combination of tests; blood test, neck fold measurement, height baby and age mother. Together these tests give an indication for a deviation.
In general, the neck fold measurement is done between weeks 11 and 13 of the pregnancy. This is done by making a belly echo. However, if it is not clear enough, a vaginal ultrasound can be taken. There are no risks associated with this. Both a buccal ultrasound and a vaginal ultrasound do not give an increased risk of miscarriage.
Beforehand, the length of the baby is determined exactly once again, by drawing a line from the skull to the end of the spine. Then the width of the neck fold is measured. You have to imagine that the skin of the baby is white and the liquid that is in the neck fold is black. The width of the neck fold is done by pulling a line from skin to skin. This line is taken several times to ensure a correct width. You can often watch on the screen yourself.
A width of 2 millimeters is normal for 11 weeks of pregnancy. At 13 weeks this is about 2.8 millimeters. A neck fold above 3 millimeters gives an indication of an increased risk. Nine out of ten cases of measurements between 2.5 and 3 millimeters are healthy. A neck fold measurement does not provide any certainty. By doing further research it can be definitively demonstrated whether the baby has a deviation.
The neck fold measurement (in combination with the other tests) says something about Down syndrome, Patausyndrome and Edward syndrome. The blood test as part of the combination test is done between week 9 and 14 of the pregnancy