Antenatal growth of the corpus callosum

OBJECTIVE: Our objective was to describe the antenatal growth of the corpus callosuni in uncomplicated pregnancies as visualized by ultrasound. STUDY DESIGN: The length of the corpus callosum was measured in the sagittal plane in 1058 sonographically normal fetuses from 13 to 38 weeks gestation using magnification ultrasound imaging. A 7 MHz, 19 mm endovaginal probe was used for vertex presentations, and a 5 MHz, 82 mm linear probe or 7 Mhz, 34 mm curvilinear probe was used for nonvertex presentations. RESULTS: The corpus callosum was clearly visualized in 68% of routine ultrasound exams between 13 and 38 weeks of gestational age. Growth was non-linear, with maximal growth occurring at 19.6 weeks gestational age. CONCLUSION: Non-linear growth of the corpus callosum is consistent with the saltatory nature of cerebral development. The period of maximal growth occurs during the first phase of neuronal migration. Since the morphology of the corpus callosum has been related to brain mass, prenatal sonographic measurement of the corpus callosum may provide a simple index of cortical development.