Clinical Research Directory

Inclusion Criteria: 1. Singleton primipara 2. Aged 20-40 years 3. Pre-assessed as eligible for vaginal delivery 4. Height between 155-170 cm, BMI between 18.5-35 kg/m² 5. Cervical dilation between 2-6 cm 6. No significant history of cardiopulmonary disease 7. No history of surgical trauma 8. American Society of Anesthesiologists (ASA) Grades I-III 9. Patients are willing to participate and be able to understand and sign an informed consent form Exclusion Criteria: 1. Contraindications for spinal anesthesia, such as coagulopathy or ongoing anticoagulant therapy, infection at the puncture site, bacteremia, epidural abscess, increased intracranial pressure, severe hypovolemia 2. Physical or mental disabilities, such as scoliosis and depression, alcohol or drug abuse 3. Major organ diseases, such as hyperthyroidism, cardiopulmonary diseases, diabetes treated with insulin, and neuromuscular diseases 4. Numerical Pain Rating Scale (NPRS) \< 5 5. Refusal to participate in the study