If the difference between the two is not big and other tests are normal, temporary observation will be enough. If the difference is big or accompanied by other symptoms, further detailed examination should be conducted. Generally speaking, normal people’s kidneys may also have a big one and a small one, therefore, if the size of the fetus’s kidneys is found to be different during pregnancy checkups, but the difference is not big and other tests are normal, there is generally no need to worry too much, and follow-up observation is sufficient. However, if the difference in the size of the two kidneys is large or accompanied by other symptoms, such as separation of the renal pelvis, hydronephrosis, etc., further detailed examination, such as ultrasonography, amniocentesis, etc., should be carried out to exclude the occurrence of fetal developmental abnormality, renal atrophy, hydronephrosis and other conditions. Therefore, patients are advised to go to the hospital for detailed examination, and if there is no abnormality, regular review is sufficient. If there is any abnormality, the patient should follow the doctor’s advice and take active treatment.