Results:The mean pre-induction arterial oxygen saturation in the two groups were similar. There was a statistically significant difference in the mean SaO 2 at one minute between the two groups, with the control group being higher (97.7% ± 1.5% versus. 96.7% ± 1.5%; p-value = 0.008). The mean least SaO 2 during surgery was also higher in the control group (95.9% ± 1.5% versus 94.9% ± 2.0%, p-value = 0.015). The Apgar score of the babies at one and five minutes for the study and control group were similar. Conclusion: Healthy parturients undergoing Caesarean section under spinal anaesthesia do well without supplemental oxygen; administration of supplemental oxygen from the common gas outlet of anaesthetic machine with the breathing circuit and standard anaesthetic facemask at 4L/min causes relative desaturation.