The widening of the lateral ventricles is not directly related to the week of gestation, because an increase in the week of gestation does not lead to the widening of the lateral ventricles, but is often caused by the fetus itself, for example, the most common is the fetal brain abnormality, which leads to fluid on the brain, and this may lead to the widening of the lateral ventricles obviously. Women usually have to check the ultrasound in the middle and late stages of pregnancy to see the lateral ventricles of the fetus. Generally, the widening of the lateral ventricles is not particularly related to the gestational week, and the width of the lateral ventricles of the fetus should be under ten millimeters in the 38th week of pregnancy, and if it is more than that, then it is not caused by the gestational week at all, and it should be considered that it is caused by hydrocephalus of the brain, which is often caused by the unsynchronized development of the fetal ventricles and foramen ovale, and so causes hydrocephalus. Foramen ovale development is not synchronized, so it leads to the cerebral fluid can not be circulated smoothly, thus stagnant in the ventricles, it will cause the dilatation of the ventricles, for example, the most common is the fetal congenital brain structure development abnormality, or chromosomal abnormality as well as intrauterine infections, and these conditions may lead to the fetal lateral ventricles widened significantly. And the number of widened lateral ventricles is usually more than ten millimeters, so after the abnormal widening of the fetal lateral ventricles, you need to consider going to the hospital to do amniocentesis for further examination to confirm the diagnosis, and may also need to consider doing a fetal magnetic resonance imaging, if necessary. Once the diagnosis of fetal abnormality is confirmed and the ventricles are widened, the pregnancy should be terminated as soon as possible because there is usually no cure for this condition.