Inclusion Criteria:  Elective cesarean section; 18-40 years; Primipara; Singleton pregnancy; Sign informed consent.  Exclusion Criteria:  ASA grade III and above; Intracranial hypertension; Hypertension; Severe heart disease; Hyperthyroidism patients without treatment or insufficient treatment; Liver and kidney dysfunction; Preeclampsia or eclampsia; Mental disorder, mental retardation; Drug abuse and alcoholism; Contraindication of intraspinal anesthesia; The preoperative EPDS score ≥10; Participated in other clinical studies.