Early change in neurobehavior is strongly associated with the intelligence development of children. Previous studies reported that cesarean section itself could influence the later development of children. In addition, neuraxial anesthesia including epidural, spinal and combined spinal epidural anesthesia (CSEA) are the major forms used during cesarean delivery, and these anesthesia techniques will undoubtedly evoke hypotension and corresponding hemodynamic alteration, of which would result in decreasing in umbilical placental insufficiency and fetus hypoxia leading to early abnormality of neurobehaviors in infants. Fluid management, such as crystalloid and colloid, is the common ones given before or / and after neuraxial anesthesia to prevent or reverse hypotension. However, it is still unknown whether the perineuraxial anesthesia fluid resuscitation could improve the neurobehavior scorings, and could produce positive effect on later intelligence development. Herein the investigators hypothesized that effective perineuraxial anesthesia fluid management during cesarean section would prevent the occurrence of hypotension and improve infant's neurobehavior scorings.

Inclusion Criteria:

• 21-40 yr
• First time of delivery
• ASA status I-II
• No premature
• No genetic and infectious diseases
• Chinese

Exclusion Criteria:

• < 21 yr
• > 40 yr
• Subjects with cardiac and pulmonary disorders
• Dislocation of placenta
• Pregnant hypertension
• Allergy to local anesthetics
• Unwilling to cooperation
• With significant delivery side effects