Behavior of an anencephalic fetus studied by 4D sonography

Diagnosis of anencephaly during early pregnancy by ultrasound which is based on the demonstration of absent cranial vault and cerebral hemispheres, has been known for more than 25 years. Morphological records of abnormal and normal brain structure in anencephalic fetuses have been clearly understood. Nevertheless, there are still unknown facts about fetal behavior affected by anencephaly. Although abnormal motor behavior in anencephalic fetuses has been reported, detailed quantitative and qualitative study of the fetal behavior assessed by direct four-dimensional (4D) ultrasound does not exist. In the present case, we describe a comparison of fetal behavior between a fetus with anencephaly and a normal fetus at 19 weeks of pregnancy.