The diagnostic criteria for ventricular widening are: the width of the posterior horn of the lateral ventricle is greater than or equal to 1 cm, regardless of the gestational week. In contrast, 1 cm to 1.2 cm is called critical ventricular widening. About 40% of lateral ventricular widening is caused by abnormalities of the central nervous system (abnormal brain development, cerebrospinal bulge, cerebral hemorrhage, tumors, etc.) or outside the central nervous system, and 12% of patients have chromosomal abnormalities. Other causes include intrauterine infections (e.g. cytomegalovirus infection, toxoplasma infection and syphilis infection) and genetic mutations (male affected children, hereditary hydrocephalus). Ventricular widening occurs in approximately 0.5 to 1.5 fetuses per 1000 pregnancies. There are more boys than girls. If there is no family history or mutation in the L1CAM gene, the incidence of repeat pregnancies is about 4%. What should we do if we find ventriculomegaly? The first step is to establish a diagnosis and find the cause. Patients should go to a hospital qualified in prenatal ultrasound (e.g., Peking University Hospital) to have an ultrasound consultation with a doctor qualified in ultrasound to make a clear diagnosis and determine if there are other structural abnormalities in the fetus. Fetal MRI can also be done to assist in the diagnosis. Other etiologies include cord blood sampling to exclude fetal chromosomal abnormalities (common chromosome 9, 13, 18 and aneuploidy abnormalities such as 21-trisomy), and infection indicator tests (TORCH test). Next, seek consultation with a qualified physician to discuss the management of the pregnancy and the mode of delivery. For children with combined structural or chromosomal abnormalities in other areas, further pregnancy is not recommended. In children with simple ventricular widening, ultrasound should be performed every 2-4 weeks to dynamically detect whether the ventricles are dilated, shrinking, stable without progression or with progressive ventricular widening. About 1/3 of children will return to normal in utero and 16% may become severely enlarged lateral ventricles (≥15 mm). Intrauterine treatment (ventricular drainage), once used internationally, is no longer recommended internationally because it does not improve the fetal prognosis. During delivery, cesarean delivery is recommended if the fetal head is too large; otherwise, delivery can be attempted vaginally. After the birth of a fetus with simple lateral ventricular widening, it should be re-examined as soon as possible to clarify the diagnosis and find the cause. If significant ventricular widening is still present, early drainage (ventriculoperitoneal drainage) should be performed in pediatric surgery. In children with isolated ventricular widening, 90% of the fetuses have normal neurodevelopment. Mental development is related to the early or late drainage procedure. 10% of children may have epilepsy, motor function or intellectual impairment. Asymmetric ventricular widening, severe lateral ventricular widening, and progressive ventricular widening fetuses have poorer long-term neurodevelopment. It is important to note that the current state of technology cannot detect all fetal abnormalities during pregnancy, so we should make a well-thought-out decision.