[Nuchal translucency thickness at 11-14 weeks of gestation: French charts and equations].
OBJECTIVE
To construct French reference charts and equations for nuchal translucency thickness (NT) using a large sample of fetuses. To compare this new reference with previous ones.


METHODS
The study data were obtained from a single large screening center over seven years. Only measurements taken by trained and certified (Fetal Medicine Foundation) operators, with crown rump length (CRL) between of 45 to 84 mm were used. Multiple pregnancies, abnormal karyotype, cystic hygroma or measurements performed by operators performing less than 500 examinations over the study period were excluded. Raw centiles were computed for each CRL. They were then fitted using a least square regression model with high order polynomials. Predicted median values for NT were compared to previously published references and the impact of deviation in median NT was evaluated.


RESULTS
There were 19,198 measurements included for NT modelling. New charts and equations for NT centiles calculations are reported. Median values were comparable to those reported in other populations. The small discrepancy in median NT did not impact on screening efficiency.


CONCLUSIONS
We present new French reference charts and equations for NT at first trimester. These may serve as a basis for ongoing audit and quality control. Although they were derived from a very and unselected sample, they do not show clinically relevant difference as compared to existing references. Our results do no support the use or development of customized French reference charts and algorithm for first trimester screening.
Service de gynécologie obstétrique, CHU Necker-Enfants Malades, université Paris-Descartes, AP-HP, 75743 Paris, France.
L J
LJ
Salomon
G E
GE
Chalouhi
J-P
JP
Bernard
Y
Y
Ville
D018568:Crown-Rump Length; D005260:Female; D005602:France; D005865:Gestational Age; D006801:Humans; D016018:Least-Squares Analysis; D015233:Models, Statistical; D048208:Nuchal Translucency Measurement / Q000592:standards*; D011247:Pregnancy; D012016:Reference Values