Mild widening of the fetal lateral ventricles does not need to be controlled, but if the lateral ventricles are too wide, there is a possibility of combined fetal malformations, so it must be taken seriously. Fetal lateral ventricular widening is a common ultrasound manifestation and is generally considered to be abnormal at greater than or equal to 10mm, 10mm-12mm is considered mild, 13mm to 15mm is moderate, and greater than 15mm is severe. Mild lateral ventricular widening alone is incidental and benign, and more than 90% of fetuses can have normal neurodevelopment. However, the wider the lateral ventricle, the more likely it is that the fetus has an abnormality. At present, fetal lateral ventricle widening is considered to be associated with gestational diabetes, intrauterine infections such as cytomegalovirus and toxoplasmosis, and chromosomal abnormalities, the most common being trisomy 21. Therefore, when lateral ventricular widening is detected, it is not abnormal in mild cases, and some of them may subside naturally with the gestational age, but chromosomal tests and tests for cytomegalovirus and toxoplasmosis are still recommended. A fetal cranial MRI can also be done to rule out structural malformations of the fetus.