4-D sonography provides a means of evaluating fetal facial expression early in the third trimester. It may be a key to predicting fetal brain function and well-being and an important modality in future fetal neurophysiologic research.

Objective:  The purpose of our study was to evaluate the fetal behavioral pattern in the early second trimester of pregnancy by use of a specially developed abdominal real‐time three‐dimensional sonography. Methods:  Real‐time three‐dimensional sonographic examinations were performed on 11 normal pregnant women from 14 to 18 weeks of gestation. This imaging system provides continuous three‐dimensional sonographic images every 1–2 s. The fetal movement was monitored for 60 min in each patient, and head, mouth, arm, trunk, and leg movements were evaluated. All fetal behavioral patterns were observed during the period studied. Results:  Active phase (time with fetal movements) was 59.4%, and resting phase 40.6%. The most active fetal behavioral pattern was an arm movement, whereas the least was a mouth movement. Moreover, each fetal movement was synchronized and harmonized with other fetal movements. Conclusions:  Real‐time three‐dimensional sonography provides a novel means on the evaluation of fetal behavior in the early second trimester of pregnancy. These results suggest that real‐time three‐dimensional sonography become an important modality in future early fetal behavior research and in evaluation of fetal well‐being in the second trimester of pregnancy.

Our findings suggest that liver volume may be a useful measurement for diagnosing small-for-gestational-age fetuses in the mid to late third trimester but that liver length may not be predictive. Further studies involving a larger sample size would be needed to confirm this suggestion.

Dynamic three-dimensional sonography provides a novel means for evaluation of fetal behavior in the early second trimester of pregnancy. These results suggest that dynamic three-dimensional sonography may be an important modality in future early fetal behavior research and in evaluation of early fetal well-being.

Our findings suggest that the standard curve for the fetal splenic volume using three-dimensional ultrasound provides a superior means for evaluating the normal splenic growth in the fetus and for identifying splenic abnormalities in utero. However, the data and its interpretation in our study should be taken with some degree of caution because of the small number of subjects studied. Further studies involving a larger sample size would be needed to confirm these findings.