Under normal circumstances, the width of lateral ventricles is not more than 1cm. If 4D ultrasound shows that bilateral lateral ventricles are 1.1cm wide, which is a slight dilatation, it may be caused by excessive cerebrospinal fluid, and requires regular observation. If it is not self-absorbed, it is necessary to do a fetal cranial magnetic examination to check for the presence of hydrocephalus. Fetal ventricular width refers to the excess cerebrospinal fluid in the fetus, which accumulates inside the ventricles, causing the ventricles to dilate and widen. Any ventricular width less than 1.5 cm is considered mild dilatation, and a ventricular width of 1.1 cm may gradually recover with self-absorption of the cerebrospinal fluid, so it should be checked regularly during labor and delivery and observed periodically. If there is no self-absorption or persistent widening, hydrocephalus is likely to be present, and further fetal cranial magnetic examination is needed to clarify the diagnosis, and amniocentesis is also needed to check for chromosomal disorders if necessary. Pregnant women are advised to undergo regular checkups to determine the growth and development of the fetus, and to seek prompt medical attention if there is any abnormality, so as to ensure the smooth delivery of the fetus.