Fetal Habituation

Abstract

One aim of obstetric practice is to ensure the wellbeing of the fetus. This is by no means an easy task and recent years have seen the development of a variety of tests, with varying degrees of success, to evaluate fetal health.Fetal wellbeing may be assessed at a variety of levels: genetic/cellular, physical/structural or functional. Ideally the evaluation of fetal health should provide information about the functional outcome of any particular condition, especially the performance of the central nervous system. Current tests may not do this. Thus, whilst tests of the fetal chromosomal or genetic constitution may determine the presence of particular genetic/chromosomal conditions, they may not predict functional outcome especially the functioning of the cerebral cortices, the ultimate arbiter of excellence in man. For example, Down's syndrome may be accurately diagnosed by analysis of fetal cells to detect the presence of Trisomy 21 but this in itself provides little information on the subsequent functional performance of the individual. The development of tests of fetal heart function such as antenatal cardiotocography have provided a means of assessing cardiac function and, to a certain extent, the functioning of parts of the autonomic nervous system. However such tests can only indirectly assess cortical function.

Four‐dimensional sonographic assessment of fetal facial expression early in the third trimester

“…Regular mouthing and nonrapid eye movement (state 1) appear at about the same time, from 35 weeks on [10]. The different phases of behavior are thought to reflect different levels of brain activity, as fetal habituation may implicate the function of the cortices [16]. Nonrapid eye movement sleep may be an indication thalamocortical pathway function.…”

Behavior During the Prenatal Period: Adaptive for Development and Survival

“…Researchers have been interested in the fetus's ability to learn (15), perhaps because of its importance for individuals after birth. Leader and colleagues demonstrated the ability of the fetus to habituate, beginning at 22 to 24 weeks GA (24; see also 25). The fetus has also been classically conditioned (26).…”

Sex differences in fetal habituation

“…Habituation can be defined as the decrease in response to the repeated presentation of a stimulus (Thompson & Spencer, 1966). It is considered a basic form of learning (Hepper & Leader, 1996; Jeffrey & Cohen, 1971; Thompson & Spencer, 1966) and serves a key function in that it enables the individual to adapt to its environment (Glaser, 1966). In survival terms, with limited ‘attentional’ resources, habituation enables attention to be removed from constant, unchanging, stimuli to the detection of new stimuli which may be dangerous (Hepper & Leader, 1996).…”

“…In 1982, using the more modern technology of ultrasound to observe directly the fetus’ response, Leader and colleagues documented that repeated presentation of a sound stimulus initially elicited a large movement response from the fetus but with repeated presentations the response waned and eventually ceased (Leader, Baillie, Martin & Vermeulen, 1982a). Since these observations there have been many demonstrations of habituation by the fetus to sound stimuli (for review, see Hepper & Leader, 1996).…”