Development of Fetal Movement between 26 and 36-Weeks’ Gestation in Response to Vibro-Acoustic Stimulation

Abstract

Background: Ultrasound observation of fetal movement has documented general trends in motor development and fetal age when motor response to stimulation is observed. Evaluation of fetal movement quality, in addition to specific motor activity, may improve documentation of motor development and highlight specific motor responses to stimulation. Aim: The aim of this investigation was to assess fetal movement at 26 and 36-weeks gestation during three conditions (baseline, immediate response to vibro-acoustic stimulation (VAS), and post-response). Design: A prospective, longitudinal design was utilized. Subjects: Twelve normally developing fetuses, eight females and four males, were examined with continuous ultrasound imaging. Outcome Measures: The fetal neurobehavioral coding system (FENS) was used to evaluate the quality of motor activity during 10-s epochs over the three conditions. Results: Seventy-five percent of the fetuses at the 26-week assessment and 100% of the fetuses at the 36-week assessment responded with movement immediately following stimulation. Significant differences in head, fetal breathing, general, limb, and mouthing movements were detected between the 26 and 36-week assessments. Movement differences between conditions were detected in head, fetal breathing, limb, and mouthing movements. Conclusion: Smoother and more complex movement was observed with fetal maturation. Following VAS stimulation, an immediate increase of large, jerky movements suggests instability in fetal capabilities. Fetal movement quality changes over gestation may reflect sensorimotor synaptogenesis in the central nervous system, while observation of immature movement patterns following VAS stimulation may reflect movement pattern instability.

Physiological reactivity of pregnant women to evoked fetal startle

“…Fetal motor activity was elicited at both 24 and 36 weeks while a fetal heart rate response was isolated to the latter gestational age. This is consistent with other reports that note changes in responsiveness to airborne or vibratory stimuli with advancing maturation [38, 41, 48, 63]. While the significantly greater fetal motor response observed at 24 weeks may be somewhat counter-intuitive to a maturational phenomenon, it was attributable to a prolonged period of motor activity following stimulation.…”

“…The fetal response to brief application of vibroacoustic or auditory stimulation has been well documented in academic literature as early as the 1930’s [37]. Examples of vibroacoustic stimuli applied directly to the maternal abdomen have included those designed for obstetric purposes to stimulate a dormant fetus [38–41], an electronic artificial larynx [42, 43], and other devices that emit vibrations [44, 45]. In general, fetuses respond to initial applications of vibroacoustic stimuli with transient increases in fetal motor activity and heart rate, consistent with a startle response.…”

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“…Spontaneous motor activity commences during the late embryonic period, and by the 16 th week of gestation the fetus shows a range of motion of the limbs, fingers and head, including stretching, yawning, hand to face contact, swallowing and tongue protrusion. In general, fetal movement progresses from uncoordinated movements that involve the entire body to more integrated and fluid behavior patterns progressing from least to most well differentiated (Amiel-Tison et al, 2006; Birnholz, Stephens, & Faria, 1978; deVries et al, 1982; Grant-Beuttler et al, 2011; Kurjak et al, 2006; Roodenburg et al, 1991). Readers are directed to a comprehensive synthesis of the emergence of human motor function by (Einspieler, Prayer, & Prechtl, 2012).…”

Dopamine receptor polymorphism modulates the relation between antenatal maternal anxiety and fetal movement

“…This finding might contribute to the higher rate of movement shown by fetuses with a 7R allele and an anxious mother. Taken together, the profile of results, specifically the higher Movement Frequency of the fetuses of anxious mothers without effects on measures of duration, could reflect the net influence of stress on fetal reactivity without effects on movement complexity, which likely would have increased the duration of movements and correlates with the neuromaturation of the fetus (Grant‐Beuttler et al, ).…”