Whether fetal left ventricle 10mm wide is serious needs to refer to the patient’s condition, some fetuses are not serious, some fetuses are relatively serious and need timely treatment. Fetal lateral ventricular widening is characterized by ventricular dilatation and is a common prenatal ultrasound finding. Mild (10-12mm), moderate (13-15mm), severe (>15mm) There are several possible causes: 1 Structural malformations: structural malformations leading to widening of the lateral ventricles include:hypoplasia of the corpus callosum, Dandy- Walker malformation, and neural tube defects. The most common cause of severe lateral ventricular widening is narrowing of the middle cerebral aqueduct. 2 Infections: CMV (cytomegalovirus), Toxoplasma gondii, zaka virus (most often in combination with other ultrastructural malformations) 3 Genetic disorders: isolated mild-severe 5% chromosomal nuclear abnormalities; 10%-15% fetal chromosomal microarray abnormalities. If there is no combination of other anomalies, the prognosis of simple mild widening of lateral ventricles is good, and most of them can disappear on their own after birth. For example, if the left ventricle of the fetus is 10mm wide and continues to grow with the continuation of pregnancy, or if the fetus combines with the anomalies of other structural systems, the situation is relatively serious, and it is necessary to further improve the cranioencephalographic examination of the fetus, and amniocentesis, etc., to exclude the fetal anomalies. When abnormalities occur, patients should be actively treated under the guidance of specialized physicians to avoid delaying the condition and leading to adverse pregnancy outcomes.