Objective: To evaluate the frequencies of fetal facial expressions among appropriate-for-gestational-age (AGA), small-for-gestational-age (SGA), and growth-restricted (FGR) fetuses.
Methods: Four-dimensional (4D) ultrasound was used to examine the facial expressions of 50 AGA, 25 SGA, and six FGR fetuses between 28 and 35 weeks of gestation. The frequencies of seven facial expressions during 15-minute recordings were assessed. Comparison of facial expressions among the three groups was performed.
Results: Mouthing was the commonest facial expression at 28-35 weeks, and the frequency of mouthing was significantly higher than those of the other six facial expressions in AGA fetuses. Mouthing was the most frequent facial expression, but there was no significant difference in the frequency among mouthing, smiling and blinking in SGA fetuses. Moreover, mouthing displayed a significantly higher frequency than the other facial expressions, except for yawning, smiling, and blinking in FGR fetuses. However, there was no significant difference in the frequency of each facial expression among the three groups.
Conclusions: Our results suggest that the frequencies of fetal facial expressions are not decreased in either SGA or FGR pregnancies. The absence of a decrease in the frequency of each fetal expression in FGR fetuses may be due to increased brain blood flow because of the brain-sparing effect. Moreover, accelerated maturation and development of the brain function, especially the central dopamine system, might be suspected in SGA and FGR fetuses.
Keywords: 4D ultrasound; AGA fetus; FGR; SGA fetus; fetal facial expression.