Aim : The aim of the study was to observe different expressions and movements of a fetal face during investigation of fetal behavior in the second and the third trimester of normal pregnancies, as a probable manifestation of fetal awareness. Subjects and methods : Over a 6-month period a study was conducted in three centers in Zagreb, Croatia and in Barcelona and Malaga, Spain. Women with singleton pregnancies (16–33 weeks) who were referred for ultrasound check-up for determination of gestational age, suspicious fetal malformations, polyhydramnios, and/or the assessment of biophysical profile or other possible pathology, were assigned to the study. After regular two-dimensional (2D) ultrasound assessment at an antenatal clinic, pregnant women were offered the possibility of undergoing 4D ultrasound examination if the fetus and the mother were considered “normal”, i.e., if ultrasound and clinical assessment were uneventful. If the newborn delivered at term had 1- and 5-min Apgar scores of 7 and 10, respectively, and if the newborn was considered “term and normal” (normal spontaneous activity, normal posture and tone, and presence of some primitive reflexes) at the first and subsequent regular check-ups, the inclusion criteria were deemed to have been met. Out of 119 patients, 99 fulfilled the inclusion criteria, 40 of whom were in the second, and 59 in the third trimester of pregnancy. A Voluson 730 Expert system with a transabdominal 5-MHz transducer was used for 4D ultra- sonography. After regular 2D scanning, the 4D mode was switched on, and a live 3D image was reconstructed by selecting ideal 2D mid-sagittal images of the face (the region of interest). The volume was automatically scanned every 2 s while the surface-rendered mode was switched on, and 4D images were displayed on the screen and recorded on videotape during a 30-min observation period. Movements of the following fetal face structures were analyzed: forehead, brows, nasal soft tissue and nasolabial folds, upper lip, oral cavity and tongue, lower lip and chin, eyelids and eyes, mouth and mouth angles, and facial expression. 4D ultrasonography allowed in utero observations of fetal facial expressions such as smiling, yawning, and swallowing. Results : The quality of 4D depiction of fetal facial expressions increased with gestational age. The frequency of fetal facial expressions such as yawning ranged from 1 and 6 with a median of 1.5 per 30-min observation period; smiling ranged from 2 and 8 with the median of 2; tongue expulsion ranged from 2 to 6, median 3; mouth and eye squeezing ranged from 5 to 10, median 6; scowling ranged from 1 to 3, median 0.5; and isolated eye blinking ranged from 4 to 12 with a median of 5. Conclusions : Our study shows the ability of 4D sonography to depict different facial expressions and movements, which might represent fetal awareness. Never-theless, long, precise and thorough observation of fetal faces by 4D sonography was hampered as the images were only near real-time. Thus, we were only able to study the quality and not the quantity of facial movement patterns.