[Physiology of intrauterine fetal activity].

Development of heart motions and fetal body movements are detectable by ultrasound in early gestation period. There is no identifiable triggering mechanism, thus these motions are attributed to an intrinsic autonomic mechanism. These spontaneous motions controlled by endogenous mechanisms of central nervous system represent neural functions. Most--if not all--intrauterine movements are brought about by endogenous factors through intrinsic motivation. Early intrauterine movements usually involve the whole body musculature. Initially, these are arrhythmic in nature and occur sporadically. Independent movements of extremities can be observed between the 9th and 12th gestational weeks. Frequency of movements increases between 24th and 28th weeks, then decreases between 30th and 39th weeks of gestation. External stimuli such as touch, pressure, sound or temperature change can stimulate reactive body movements. The development, organization and co-ordination of body movements are studied by ethologists, while the frequency of movements is the subject of interest of obstetricians. Although these investigations have different aims, researches often overlap in the absence of clearly identifiable borderlines. As obstetricians are rather interested in the second half of the pregnancy, 80% of relevant publications refer to this period of pregnancy.