Clinical Study

Nomogram for measurements of the fetal maxillary bone during the first trimester screening for Down syndrome

  • Derya Sivri
  • Murat Api
  • Ahmet Çetin

Received Date: 25.01.2007 Accepted Date: 30.03.2007 J Turk Ger Gynecol Assoc 2007;8(4):374-379


To define a nomogram of fetal maxillary bone length for a Turkish population between 11 and 13+6 weeks’ gestation.


This was a prospective observational and cross-sectional study over 12 months examining Turkish women with a singleton pregnancy who attended the first-trimester screening program for Down syndrome. Consecutive routine biometric measurements and fetal organ scans were obtained from patients. Special attention was paid to the profile view of the fetal face, and the maxillary bone was identified and measured.


Four hundred and three fetuses between 11 and 13+6 weeks’ gestation were scanned. The maxillary bone is seen as a rodlike structure; it is a part of the facial skeleton that allows the opening and closing of the pharynx. A linear growth function was observed across gestational age, and good correlation was found to exist between crown-rump length (CRL) and the maxillary bone (r=0.662; p<0.0001; y=2.328+0.068xCRL). Significant correlation was also found between the maxillary bone and biparietal diameter (BPD) (r=0.693; p<0.0001; y=1.703+0.226xBPD), head circumference (HC) (r=0.704; p<0.0001; y=1.380+0.066xHC), femoral bone length (FL) (r=0.678; p<0.0001; y=4.303+0.287xFL), and abdominal circumference (AC) (r=0.705; p<0.0001; y=1.552+0.081xAC).


Normative data for sonographic measurements of the fetal maxillary bone between 11 and 13+6 weeks’ gestation are provided. These data potentially allow the prenatal diagnosis of abnormal maxillary bone length.

Keywords: Fetus, maxillary bone, prenatal diagnosis; ultrasonography