Facial shape; height and width in the second and third trimester of pregnancy

Objectives: The objective of this study is to calculate on 3D volumes obtained from 16 weeks' gestation normative data of facial height (FH), facial width (FW) and their ratio and to test these parameters in pathological cases. Methods: In total, 228 volumes were analyzed: 207 from normal and 21 from pathological cases. After multiplanar correction to the exact midsagittal plane FH was measured from the nasion to the gnathion and FW between the most lateral points on the zygomatic arch. Results: For both FH and FW the intra- and inter-observer intraclass correlation coefficient variability was 0.99 and the difference between paired measurements was less than 0.3 cm in 95% of the cases. FH increased from 1.48 to 5.08 cm (FH = -16.10 + 3.78 x log(GA), R-2: 0.93) and FW from 2.20 to 6.42 cm (FW: 4.19-17.18 x log(GA), R-2: 0.85). The ratio increased steadily until about 25 weeks and less thereafter (ratio: (1/GA) x 26.44 + 0.92, R-2: 0.23). In pathological cases 16.6% of measurements were outside the normal range. Conclusions: This study provides normative data for FH and FW measurements and insight in normal facial growth after 16 weeks' gestation. FH exceeds FW growth especially before 25 weeks.