Aim: To determine the distribution of cerebral lateral ventricular atrium width (LVAW) as established according to gestational weeks, and calculate the criterion value of LVAW that differentiates normal fetuses from abnormal fetuses. Materials and Methods: A total of 832 patients meeting the study's criteria were included in the control group. An additional 43 fetuses with LVAW > ten mm formed the case group. Results: The criterion value of LVAW was 9.7 mm. It did not change significantly throughout gestation. In the case group, 23 fetuses were terminated for fetal abnormalities, two fetuses died in utero, and 18 infants were born alive. Most of the abnormal development coincided with LVAW values greater than 12 mm. Conclusion: The authors suggest 9.7 mm as the criterion value, based on receiver operating characteristic (ROC) curve analysis. When the LVAW is between 9.8 and 12 mm without other fetal abnormalities, it may be regarded as a variation of the normal.