Intraoperative supplemental oxygen has been given for most parturients undergoing cesarean section under spinal anesthesia. However, evidences supporting the practice is not clear nowadays, especially for healthy parturients who are monitored continuously with pulse oximeter. Furthermore, hyperoxia may produce free radicles which could harm fetus and newborns.

Changing practice is not that easy. This study has been conducted to prove that supplemental oxygen is not necessary for healthy parturients during cesarean section.

Supplemental oxygen has been routinely given to parturients because doctors were concerned about desaturation. However, the evidences for giving oxygen was not strong, and the condition nowadays can be detected immediately with pulse oximeter which is a standard monitoring.

After this study finished, we will set a safety guideline for supplemental oxygen for healthy parturients undergoing elective cesarean section.

Inclusion Criteria:

• Aged > 18 years old.
• Term pregnancy (gestational age 37 -42 weeks).
• Singleton
• Elective cesarean section.

Exclusion Criteria:

• History of infertility
• Diabetes
• Hypertension or preeclampsia
• Heart disease
• Morbid obesity
• Premature rupture of membrane
• Placenta previa
• Preoperative oxygen saturation < 95%