Behavioral parameters assessing human fetal development

Fetal behaviors gradually integrate into more complex movements in relation to each other along with functional central nervous system development. Investigating the ontogenesis of fetal behavior made it possible to allow prenatal localization of functional brain impairment, however, it is still difficult to deduce higher brain function in human fetuses. Fetal learning has the potential to be a new parameter to deduce higher brain function in the human fetus. We investigated fetal learning from a behavioral development perspective assessed by a conventional parameter, i.e. eye movement patterns. After at least 32 weeks of gestation, the fetuses presented habituation to vibro-accoustic stimulation. Fetuses less developed required significantly more trials to show habituation than developed fetuses from a behavioral standpoint even at the same gestational age. Three- or four-dimensional ultrasound evaluation also provides new findings in fetal behaviors in early gestation. These methods could be new parameters to assess fetal brain function, however, it is necessary to choose appropriate parameters and to develop easy and ubiquitous criteria, which cover higher brain function throughout the entire gestational stage.