The Neck fold measurement is a non-invasive examination in the 12th to 14th week of pregnancy. With the help of a high-resolution ultrasound device, the thickness of the neck fold of the unborn baby is determined. This allows conclusions to be drawn about possible genetic diseases.
What is neck fold measurement?
Between the 11th and 14th week, water builds up in the baby's neck area. If this area is enlarged, this can indicate genetic defects (e.g. Down syndrome) or heart defects. The neck fold measurement is also Neck density measurement, Neck transparency measurement or NT screening called. It is not a diagnostic method that could provide information about an actual disease. Rather, it is a statistical estimate of the baby's likelihood of malformation.
This includes not only the width of the neck folds, but also the size and age of the embryo and the age of the mother. An increased value for the width of the neck crease does not mean that the baby will be born disabled. It just says that the child is more likely to develop a malformation. Only further investigations can bring certainty. An inconspicuous value of the neck fold width is also no guarantee of a healthy child.
Function, effect & goals
During pregnancy, the unborn baby has a lymphatic system and kidneys. Until they are fully developed, the body cannot excrete any fluid that has accumulated. It accumulates in the neck between the skin and soft tissues. This crease in the neck is safe for the child and disappears again in the course of development. Neck wrinkle measurements can only be performed in two to three weeks of pregnancy. The time window for this examination is so small because the baby is too small before the 11th week of pregnancy.
This would make the measurement too imprecise. From the 14th week of pregnancy onwards, the baby's kidneys are developed and the water retention in the neck is dissolved by them. The optimal time for the examination is therefore the 12th week of pregnancy. The crease in the neck appears transparent in the ultrasound due to its fluid filling. For the examination, the gynecologist must be specially trained and have a high-resolution ultrasound device. As a rule, the ultrasound examination is carried out through the mother's building ceiling. A vaginal exam is only done if the baby is lying awkwardly. Great care is required in the implementation. So z. B. Do not set the measurement too deep in the child's neck, otherwise the value for the width would be incorrectly too high.
The aim of the neck fold measurement is not to determine the health of the child. This investigation cannot do that. It only provides statistical information about the probability that the child will be born without a disability. A value of 1 to 2.5 millimeters for the neck fold is considered normal. Values from 3 millimeters are considered increased, from 6 millimeters the value is very high. Provided that the measurement is correct, the likelihood of a malformation in the baby increases as the value of the neck fold width increases. The possible malformations are trisomy 21 (Down syndrome), trisomy 13 (Pätau syndrome), trisomy 18 (Edwards syndrome) or heart defects. Both trisomy 13 and trisomy 18 lead to severe organ malformations and a very short life expectancy, which usually does not go beyond infancy.
The measurement of the width of the neck folds does not provide any information about which undesirable development could be present. Further research is required for this. This examination is recommended for mothers aged 35 and over, if previous ultrasound examinations revealed abnormalities, in high-risk pregnancies and if there is an increased risk of genetic defects in the family. The neckfold measurement is not a standard benefit of the health insurance companies. Therefore, it is only paid for by the health insurers in exceptional cases. Affected women should, however, ask. If the examination has to be paid for yourself, the costs are between € 30 and € 200.
Risks, side effects & dangers
Since the neckfold measurement is an ultrasound examination, it is completely risk-free for mother and child. Difficult are the psychological problems and the relative uncertainty of the investigation. It very often gives false positive results. In 5% of the examinations an increased value for the neck fold width is found. Then additional research is required. Only in 10% of the cases do these examinations really reveal a disability for the baby.
On the other hand, a disability cannot really be ruled out even with a normal value for the width of the neck folds. Only an amniocentesis can provide final clarity. However, this is associated with the risk of a miscarriage. So mothers should only get a neckfold measurement if there is a real reason to do so. Otherwise it can happen that you worry unnecessarily and possibly also take unnecessary risks. You should also discuss with your partner what to do if the value increases. Do you want to take the risk of having an amniotic fluid test for clarity? How do they react when a disability is really diagnosed?
If in doubt, are you willing to have an abortion? It should also be noted that around 20% of all children born with Down syndrome do not have an enlarged neck fold. The neck fold measurement can therefore only ever be seen as an indicator of a possible disability. It creates suspicion, not clarity. This can only be obtained through additional studies.
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