The effect of behavioral state on fetal metabolism and blood flow circulation

As in postnatal life, behavioral states when evident in utero are also seen to influence the metabolic activity and/or circulation of several organ systems if not the global metabolic and circulatory activity of the fetus. In some instances this effect is organ specific as in the increased metabolic activity of the brain during the fetal REM state, which may account for the prominence of this state through the perinatal period and contribute to the brain's growth and development at this time. Generalized metabolic and circulatory effects may also be seen as associated with state-related changes in fetal biophysical activity or circulating vasoactive substances. Although the exact functions of sleep and sleep states are not yet known, their influence on the metabolic and circulatory activity of organ systems is seen to onset in early life, suggesting that a need for such may be just as important during early development as in later life.