Inclusion Criteria:  Morbid obesity parturient defined as a body mass index (BMI) above 40 kg/m2. ASA physical status I-II Age above 18 years. Scheduled for elective caesarean section under general anesthesia.  Exclusion Criteria:  Parturient of ASA physical status III or above. Suspected or known difficult airway (Mallampati class > 2, reduced neck movement, reduced mouth opening, or Cormack-Lehane grade 4 recorded during a previous intubation procedure). Any contraindication for nasal prong use, for example, tumours, fractures or trauma. SpO2 ≤ 97% prior to preoxygenation.