The main psychological tests for postpartum depression are the Hamilton Depression Inventory, the Depression Self-Rating Inventory, the PHQ-9 Depression Screening Inventory, and the 90-item Symptom Self-Rating Inventory. The Hamilton Depression Inventory is an other-rated scale that needs to be evaluated by a professional doctor, who will give the patient a score based on his or her answers and responses to questions, which can be classified as mild, moderate or severe depression. The Depression Self-Assessment Scale and PHQ-9 Depression Screening Scale are self-assessment scales in which the patient operates the computer to select the answers on the scale and the system will produce the test results after completion. 90-item symptom self-assessment scales are also self-measurement scales, including somatization, interpersonal relationships, anxiety, depression, obsessive-compulsive, fear and other factor scores, with each factor score less than or equal to 2 being normal and greater than 2 being abnormal.