Stedman's Medical Dictionary. © 2006 Lippincott Williams & Wilkins
"nuchal fold thickness
Type: Term
Definitions:
1. ultrasonographic measurement of skin thickness on the back of the fetal neck; measured from 15–22 weeks. Increased thickness indicates increased fetal risk for aneuploidy and some nonchromosomal disorders."
http://www.medilexicon.com/medicaldictionary....

"The nuchal thickness is a parameter that is measured in a second trimester scan (18 - 22 weeks) and it not to be confused with nuchal translucency (which is measured in the first trimester)."
[…]
"A thick nuchal fold is often considered the most sensitive 1 and most specific 3 (best) 2nd trimester marker for Down syndrome 1 with false positive rates as low as 1%."
http://radiopaedia.org/articles/nuchal-thickness

"Nuchal translucency screening, or NT screening, is an ultrasound test. It screens for Down syndrome (trisomy 21, meaning an extra copy of chromosome 21) and other disorders that are caused by extra copies of chromosomes (trisomy 13, trisomy 18), as well as congenital heart defects."
http://www.whattoexpect.com/pregnancy/pregnan...

"1. What is the nuchal translucency?
Nuchal translucency is the name for the normal fluid space behind the neck of a foetus (unborn baby) that can be seen on ultrasound scans.
2. What is a Nuchal Translucency Scan?
A nuchal translucency scan (also called first trimester of pregnancy screening) is carried out during weeks 11–13 of a pregnancy. The scan uses ultrasound to screen for Down syndrome, or other chromosomal or inherited conditions in the foetus."
http://www.insideradiology.com.au/pages/view....

"Blood test plus nuchal translucency scan
This involves a blood test and an ultrasound scan. All women should be offered a dating scan between weeks 8 and 14 of pregnancy, and a nuchal translucency scan between 11 weeks, 2 days and 14 weeks, 1 day of pregnancy. If you choose to be screened for Down's syndrome, the dating scan and the nuchal translucency scan can be carried out at the same time, between 11 weeks, 2 days and 14 weeks, 1 day of pregnancy."
http://www.nhs.uk/conditions/pregnancy-and-ba...
What is the nuchal translucency screening test?
This prenatal test (also called the NT or nuchal fold scan) can help your healthcare practitioner assess your baby's risk of having Down syndrome (DS) and some other chromosomal abnormalities as well as major congenital heart problems.
http://www.babycenter.com/0_nuchal-translucen...

"The 12 week nuchal scan screens for Down, Edwards’ and Patau Syndromes along with first anatomy checks and measurements of your baby."
http://www.thelondonultrasoundcentre.co.uk/fi...

"Nackentransparenz
Englisch: nuchal translucency
1 Definition
Als Nackentransparenz bezeichnet man ein passageres subkutanes Ödem, das im nuchalen Weichteilgewebe eines Fetus auftritt und dort mit Hilfe der Sonografie dargestellt werden kann."
http://flexikon.doccheck.com/de/Nackentransparenz

"Die Nackentransparenzmessung, auch Nackendichtemessung, Nackenfaltenmessung oder NT-Screening genannt, ist eine Ultraschall-Untersuchung in der Schwangerschaft, bei der die Nackenfalte des ungeborenen Kindes auf anlagebedingte Störungen, wie bespielsweise das Down-Syndrom, untersucht werden kann.
Wichtig ist bei der Messung der Nackenfalte, dass sowohl das Ultraschallgerät eine hohe Auflösung mit detaillierten Bildern ermöglicht, als auch eine entsprechend gute Schulung und Erfahrung des Arztes."
http://www.9monate.de/schwangerschaft-geburt/...

"Messung der Nackentransparenz (NT)
Durch die Messung der Nackentransparenz lässt sich die Wahrscheinlichkeit für das Vorliegen einer Chromosomenstörung oder anderer angeborener Erkrankungen beim ungeborenen Kind abschätzen.
Grundsätzlich kann eine erhöhte Nackentransparenz ein erhöhtes Risiko für u.a. folgende Chromosomenstörungen bedeuten:
• Trisomie 10
[…]
• Trisomie 21 (Down-Syndrom)
http://www.netdoktor.at/untersuchung/nackentr...

"Nackentransparenzmessung
Synonym für den Begriff der Nackentransparenzmessung werden die Ausdrücke Nackendichtemessung, NT-Screening und umgangssprachlich auch Nackenfaltenmessung verwendet. NT bedeutet nuchal translucency, also Nackentransluzenz bzw. Nackentransparenz.“
http://de.wikipedia.org/wiki/Nackentransparenz

Support new entries on this subject but not quite as suggested - I think they need to be a bit more comprehensive.
 
First of all, the term nuchal fold - die Nackenfalte could be added:
related discussion: die Nackenfalte

Secondly, the translucency that is measured:
nuchal translucency – die Nackentransparenz

And then there are various names in both languages for measurements made at this site, although the terms tend to be used interchangeably. NB Nuchal translucency is measured 11-13+6 weeks while nuchal fold thickness can be measured after this time:
“Nuchal translucency is a measurement performed during a specific period in the first trimester (11.3-13.6 weeks) and should not be confused with nuchal thickness which is measured in the second trimester”
http://radiopaedia.org/articles/nuchal-transl...

I would appreciate input on the German side whether that [ugs.] flag is really necessary.

@mpo70: "Baby-Medizin" ist ein putziger Ausdruck. Für die junge Generation, die mit Anglizismen wie "Baby-Elefanten" und "Baby-Bananen" aufgewachsen ist, muss das wie eine Spielwiese für Medizinstudenten klingen.