Objective To assess whether neurological maturation and development are accelerated in fetal growth restriction (FGR) in utero using four-dimensional (4D) ultrasound. Methods The facial expressions of 50 appropriate-for-gestational-age (AGA) and 34 FGR fetuses aged between 28 and 35 gestational weeks were assessed using 4D ultrasound. Subsequently, they were differentiated into two gestational age groups (19 aged 28-31 weeks and 31 aged 32-35 weeks in AGA, and 15 aged 28-31 weeks and 19 aged 32-35 weeks in FGR). Fifteen-minute recordings were made, and the frequencies of seven facial expressions during that time were examined. Correlation analysis was conducted to assess the changing number of significant correlations with advancing gestation in each group. Results Out of 21 combinations of facial expressions at 28-31 and 32-35 gestational weeks in AGA fetuses, there was only three significant correlations. Similarly, only one was noted out of 21 combinations at 28-31 gestational weeks, but there were seven significant correlations in FGR fetuses at 32-35 weeks (P=0.018). However, there was no significant difference in the number of correlations of facial expressions between AGA (3/21) and FGR (7/21) fetuses at 32-35 weeks of gestation (P=0.147). Conclusion Our results suggest that the number of significant correlations of fetal facial expressions in FGR fetuses increases more compared with that in AGA fetuses at 32-35 weeks of gestation. Due to the acceleration of neurological maturation and development in FGR fetuses, the control of facial expressions by the brain may be more evident compared with AGA fetuses at 32-35 weeks of gestation. However, the data and their interpretation in the present study should be taken with some degree of caution because of the small number of subjects studied. Further studies involving a larger sample size are needed to obtain strong or additional evidence.
Keywords: 4D ultrasound; accelerated neurological development; fetal brain; fetal facial expression; fetal growth restriction (FGR).