Fetal lateral ventricle width of 9mm can be reviewed after a period of time, and if it does not continue to grow, no special intervention is needed. Clinically, 10mm is considered as the upper limit of normal for lateral ventricle widening. Fetal lateral ventricle width of 9mm is still within the normal range and can be closely monitored and rechecked. Lateral ventricle width of 10~15mm is considered as ventricular widening, and more than 15mm is considered as hydrocephalus, of which 10~12mm is mild ventricular widening, and 12~15mm is severe ventricular widening. Fetal ultrasound suggests that the width of lateral ventricle of 9mm is still within the normal range, so there is no need to be overly worried, and it is sufficient to perform regular obstetric checkups, and observe the condition dynamically, and as long as it does not continue to grow, there is no need to intervene. When the widening of lateral ventricles is more than 10mm, we should go to obstetrics outpatient clinic in time, and complete the relevant examinations under the guidance of professional doctors to exclude fetal malformation, and recommend fetal cranial magnetic resonance examination and prenatal diagnosis to exclude fetal cranial structure and chromosomal abnormality.