Dimensions of the fetal facial profile in normal pregnancy.

Objective: To determine sonographic dimensions of the fetal facial profile in normal pregnancy.

Methods: This was a prospective, cross-sectional study of 397 normal healthy fetuses at 14-33 weeks of gestation. After exclusion of the small numbers of patients at the upper GAs, 379 patients between 14.0 and 26.9 weeks of gestation were included in the analyses. The sagittal plane of the fetal facial profile was evaluated using transvaginal and transabdominal ultrasound. Distances from the tip of the nose to the mouth (the line between the lips), from the mouth to the gnathion (lower chin), from the upper philtrum to the mouth, and from the mouth to the upper concavity of the chin were measured and are presented according to gestational age (GA).

Results: There was a significant linear correlation between GA and the distance from the tip of the nose to the mouth (r = 0.943; P < 0.00001; y = -37.98 + 7.54 x GA), from the mouth to the gnathion (r = 0.946; P < 0.00001; y = -46.34 + 7.95 x GA), from the upper level of the philtrum to the mouth (r = 0.71; P < 0.00001; y = 0.22 + 3.33 x GA) and from the mouth to the upper concavity of the chin (r = 0.665; P < 0.00001; y = 1.65 + 2.95 x GA). The ratio between the distance from the tip of the nose to the mouth and that from the mouth to the gnathion was also almost constant throughout gestation, as was the ratio between the distance from the upper philtrum to the mouth and that from the mouth to the upper concavity of the chin.

Conclusions: We provide normative data of the fetal facial profile across GA. Our data offer a potential tool for the prenatal diagnosis of abnormal fetal facial profile.