Effect of Sufentanil and Ropivacaine

Inclusion Criteria: 1. Patients had regular prenatal examinations at the outpatient clinic; 2. They were between 25 to 35 years of age) 3. They had a gestational age ≥37 weeks and \< 42 weeks; 4. They had an estimated fetal weight ≥ 2,500 g and \< 4,200 g. Exclusion Criteria: * a history of spinal surgery, * platelet count \<100×109 /L , * coagulation disorder, * sensorimotor disorder of lower extremity, * leg pain, * puncture point infection, * heart disease history, * pulmonary disease, * liver and renal function disorder and * a history of neuropsychiatry drugs.