ABSTRACT
Characterizing human fetal development poses one of the great challenges for modern biology. Scientists have long recognized the fetal period to be critical for the proper formation of organs and limb buds. However, in the past two decades, psychobiologists have stimulated an appreciation of the fact that prenatal life is not just a time of passive growth, but is also the period when developmentally diverse systems coalesce to form an organized, environmentally responsive organism. Among the first observations that contributed to this more enlightened view of the fetus were the classic studies of Nijhuis, Martin, and Prechtl (1984). These studies showed that during the later stages of fetal development there are cyclic patterns of activity within particular physiologic systems and that with maturation, these disparate activities become synchronized and behavioral states emerge. It is now widely held that the expression of these temporally organized, coherent states represents one of the earliest markers of fetal well-being and central nervous system integrity.
