The best time to check the fetal lateral ventricle is 20 weeks-24 weeks of pregnancy, if there is any abnormality, it is recommended to review at 30 weeks-32 weeks of pregnancy. Generally, ultrasound examination of lateral ventricles is performed at 20 weeks-24 weeks of pregnancy, and the normal value of fetal lateral ventricles is less than 1 cm, if the width of lateral ventricles is more than 1.5 cm, it suggests that the lateral ventricles are widened, if the deviation is smaller, it can be rechecked at around 32 weeks of pregnancy; if the deviation is larger, it is recommended to further perform amniocentesis to determine whether there is any chromosomal abnormality of the fetus, and in serious cases, even need to terminate the pregnancy. Fetal lateral ventricle widening usually improves from 28 weeks to 32 weeks, and the fluid in it is gradually absorbed at a faster rate, and most fetuses can absorb it by themselves. If hydrocephalus is still present at this time, it is recommended that the pregnant woman should have regular ultrasound checkups and choose whether to continue the pregnancy under the guidance of her doctor. In conclusion, the best time to check the lateral ventricles is between 20 weeks and 24 weeks. At this time, widening of the lateral ventricles of the fetus is relatively common, and physiological factors are mostly involved, so it is recommended that pregnant women do not need to be too nervous. Pregnant women with widening of the lateral ventricles are advised to consult a doctor for further clarification of the cause of the widening and the degree of widening under the doctor’s guidance, and to choose observation or further improvement of the examination.