Despite the longstanding conclusion that behavior can reveal aspects of underlying anatomy and function, no generalized antenatal behavior screening has been developed to identify fetuses that may have central nervous system defects requiring further evaluation. We devised a brief ultrasound examination to distinguish fetuses with compromised central nervous system function from the general population and evaluated it with this study. The study design compared behavioral findings obtained by retrospectively reviewing the ultrasound examinations of 5 fetuses that had abnormal behavior with prospectively obtained findings of 29 normal fetuses. Median time for brief examination criteria was 50 min (range, 30-60 min). The only case undetectable by this brief ultrasound examination has an eye-movement period significantly longer than the normal upper limit. Using this method as a screening test may make it possible to include assessment of fetal brain function as part of routine antenatal care.