The assessment and significance of habituation to a repeated stimulus by the human fetus.

Habituation is the progressive decrease in response by an organism when it is stimulated repeatedly. This process is a basic form of learning and a normal pattern may be one indication of intact central nervous system function. This study assessed habituation of a behavioral response by the human fetus to repeated vibrotactile stimuli. Of the 40 normal fetuses studied 37 habituated after 10 to 50 stimuli. The gestational age at which the fetus first responded to the stimulus ranged from 22 to 30 weeks. Female fetuses responded 2 weeks earlier than males. The possible value of this assessment in obstetrical practice is presented.