[Paradigms of fetal ethology].
In utero, the fetus is protected against biological and social influences of the outside world. This circumstance offers an opportunity for sonographic investigation of inherited fetal behavior free of extraneous effects. Observation of fetal activities with ultrasound permits the recognition of certain uniform features of fetal behavior. Immediately after birth, the neonate continues repeating those activities that he/she became accustomed to in the womb. Later these become modified by environmental influences. Nonetheless, basic inherited behavioral characteristics continue to be expressed and may remain recognizable even during adulthood. Some aspects of adult behavior may derive from experience acquired during fetal life. These include the hand-face reflex, various types of facial expression, such as smiling, crying, yawning, grimaces of dissatification and desperation as well as sticking out one's tongue.