The purpose of this study is to assess the prevention and treatment effect of transcutaneous acupoint electrical stimulation on hypotension after intraspinal anesthesia.

After being informed about the study and potential risks, all patients giving written informed consent will undergo the doctors' and researchers' examination to determine eligibility for study entry. At beginning of the study, patients who meet the eligibility requirements will be randomized in a open manner（participant and electroacupuncture executor）in a 1:1 ratio to TEAS group (10 minutes before intraspinal anesthesia, bilateral Neiguan points and Zusanli points are given dense wave transcutaneous acupoint electrical stimulation with the frequency of 10/50Hz. The intensity is based on the maximum tolerance of the participant, and the stimulation last until 30 minutes after subarachnoid administration) or Control group (Electrodes are connected at bilateral Neiguan points and Zusanli points 10 minutes before intraspinal anesthesia, but no transcutaneous acupoint electrical stimulation is given, the duration is the same as that of the TEAS group).

Inclusion Criteria:

• 18 years ≤ age < 55 years
• ASA classification I ~ II
• full term (37 weeks ≤ gestational weeks < 42 weeks)
• fchedule for elective single cesarean section under spinal anesthesia
• no other clinical trial 3 months before the enrollment
• volunteer to participate and sign the informed consent form

Exclusion Criteria:

• severe preeclampsia or hypertension
• diabetes
• cardiac insufficiency
• mental abnormality or cognitive impairment or inability to communicate
• acupuncture points skin breakage, infection, allergy
• the researchers believe that there are any conditions that are not suitable for inclusion.