Checking fetal intelligence during pregnancy is mainly done through Down’s syndrome screening to promptly detect mental retardation caused by chromosomal disorders such as trisomy 21, while there is generally no effective means of checking for fetuses with other causes of mental retardation. If the fetus is found to be in the high-risk group, amniocentesis or non-invasive DNA testing should be performed in a timely manner. In addition to the above tests, ultrasound is also a commonly used test during pregnancy. During the examination, the cranial structure of the fetus can be known, and the intellectual development of the fetus is closely related to the cranial structure. Therefore, as long as the cranial structure develops normally, the intellectual development of the fetus may be normal, but if there is any structural abnormality, it should be taken seriously.