Objective: To determine whether Fetal Growth Restriction (FGR) fetuses have less facial expressions than Appropriate-for-Gestational Age (AGA) counterparts with the assessment by four-dimensional high-definition live (4D HDlive) ultrasound.Methods: 4D HDlive ultrasound examinations of fetal facial expressions were performed on singleton pregnant women between 26 and 39 weeks of gestation. The duration of the 4D HDlive recordings was 15 minutes in all cases. The frequency of seven types of previously-reported facial expressions, or blinking, mouthing, yawning, tongue expulsion, sucking, smiling and scowling, were assessed. Two observers counted the frequencies, and inter-and intra-observer reproducibility was examined. Wilcoxon rank-sum test was used for comparison of FGR and AGA group. Kruskal-Wallis test was used for intra-group significance of frequencies of seven types of fetal facial expressions. P<0.05 was considered significant.
Results:In this study, good intra-and inter-class correlation coefficients and intra-and inter-observer agreements were obtained. Thus, measurement values by only one examiner were used for further analysis. The facial expressions of 16 fetuses (FGR: n=8, AGA: n=8) were assessed. We noted a tendency for FGR fetuses to have less facial expressions than AGA counterparts. Although statistically significant inter-group difference was not detected in frequency of any facial expressions, this propensity is conspicuous in smiling (p=0.065) and mouthing (p=0.279). In AGA fetuses, the commonest facial expression was mouthing and was significantly more frequent than blinking (p=0.007), tongue expulsion (p=0.007) and sucking (p=0.002). We also noted a tendency that the frequency of facial expressions declines with fetal maturation. Although no statistically significant difference was shown, this propensity is prominent in mouthing of FGR (p=0.071).
Conclusion:4D HDlive ultrasound provides promising modalities in novel evaluative imaging of fetal various facial expressions, and may help to elucidate functional development of Central Nervous System (CNS) and facial expressions both in normal and compromised fetuses.