【Objective】 To explore the effects of different inspired oxygen concentration on nulliparas and neonatus during Cesarean Section. 【Methods】 30 cases of full-term women undergoing elective cesarean delivery

after admission were randomly allocated to Ⅰ

Ⅱ

Ⅲ(10 in each). I was given air group

Ⅱ was given 30% oxygen group

Ⅲ was given 50% oxygen group. Blood pressure

heart rate differences at perioperation were record. The Apgar scoring

the concentration of the protein S100B in serum

UCBLAV and difference in blood gas at 1 min and 5 min of 3 group of neonatuses were compared. The placental tissue near the umbilical cord for immunohistochemical staining were extracted. The placental villous capillaries were measured using stereological method. 【Results】 Among 3 groups of patients

differences of HR

SBP

and SpO2 were not statistically significant (P > 0.05). Among 3 groups of neonatuses

differences of the Apgar scoring

pH

PaCO2

PaO2

Hct and Hb of umbilical arterial blood taken at 1 min and 5 min

the concentration of the protein S100B in serum were not statistically significant (P > 0.05). Among 3 groups of patients

UCBLAV

volume and density of placental capillaries of III was higher than Ⅰ and Ⅱ

with statistical significance (P < 0.05); while difference of the length of placental capillaries was not statistically significant (P > 0.05). 【Conclusion】 During perioperation

different inspired oxygen concentration increase in oxygen content. breathing 30% and 50% concentration of oxygen could similarly increase fetal oxygenation but cause a concomitant increase in oxygen free radical activity in neonatus

therefore it is recommended for breathing 30% concentration of oxygen during perioperative cesarean section.