The fetal profile line: a proposal for a sonographic reference line to classify forehead and mandible anomalies in the second and third trimester.

Objectives: To test the fetal profile (FP) line, defined as the line that passes through the anterior border of the mandible and the nasion, as a reference line for forehead and mandible anomalies.

Methods: Volumes of 248 normal and 24 pathological fetuses (16-36 and 19-37 weeks' gestation, respectively) were analysed retrospectively. When the FP line passes anteriorly, across or posteriorly to the frontal bone, this was defined as 'negative', 'zero' or 'positive', respectively.