The prenatal diagnosis of micrognathia is usually based on a subjectiv
e impression of the size of the jaw when examining the fetal profile.
We have constructed a centile chart for mandibular length between 12 a
nd 27 post-menstrual weeks in a cross-sectional study of 184 fetuses.
The application of this chart in clinical practice may permit a more o
bjective diagnosis of micrognathia in the prenatal period.