Sonographic imaging of the fetal face and the establishment of normative dimensions for chin length and upper lip width.

Sonographic imaging of the fetal face is important because a number of chromosomal aberrations are associated with facial malformations. Prenatal diagnosis of abnormalities of the fetal chin and lips have been based on subjective assessment. The purpose of the current study was to establish normative dimensions for the objective assessment of the fetal face. A cross-sectional study was performed in 200 normal healthy singleton pregnancies between 16 and 38 weeks' gestation. Inclusion criteria included performance of a first or early second-trimester scan to confirm gestational age (GA). Exclusion criteria included birth weight < 10th or > 90th percentile for GA, and medical complications of pregnancy. Ultrasound measurements were made in the mid-sagittal plane and included chin length (CL) and upper lip width (ULW). A first-degree linear growth function was observed throughout pregnancy between GA and ULW (r = 0.87) and CL (r = 0.91). All measured data are expressed as mean +/- 2 SD. In conclusion, these results provide normative dimensions throughout gestation for the fetal upper lip and chin. These data are expected to serve as a basis for the objective assessment of the fetal face in high-risk conditions.