The fetal mandible: an in utero sonographic evaluation between 11 and 31 weeks' gestation.
OBJECTIVE
To construct a growth chart of the mandible throughout gestation.


METHODS
A prospective cross-sectional study of normal singleton pregnancies was conducted. Measurements of the fetal mandibular transverse and antero-posterior diameters were performed with high-resolution transvaginal and transabdominal ultrasonography in 490 pregnant women with singleton low-risk pregnancies between 11 and 31 weeks' gestation.


RESULTS
The mandibular transverse and antero-posterior diameters were recorded by week of gestation and the ratio was calculated: mandibular ratio (MR) = 1.7759 - 0.01047 x gestational week. There was a negative linear correlation (-1.047%) for each incoming week of gestation. Normal values (+/-1SD and 2SD) were established.


CONCLUSIONS
The present data provides a normal range of fetal mandibular diameters during normal pregnancies and introduces a new parameter, the mandibular ratio, for the intrauterine assessment of the fetal mandibular development.
Zalel
Yaron
Y
Department of Obstetrics and Gynecology, The Chaim Sheba Medical Center, Tel-Hashomer, Tel-Aviv University, Ramat Gan, Israel. zalel_y@netvision.net.il
Gindes
Liat
L
Achiron
Reuven
R
D003430:Cross-Sectional Studies; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D008334:Mandible / Q000000981:diagnostic imaging* / Q000196:embryology*; D011247:Pregnancy; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal