Objective:  To determine the effectiveness of oxygen inhalation after delivery in reducing vaginal blood loss during the third and fourth stages of labour.
Methods:  In this prospective randomised trial, 450 women undergoing vaginal delivery who did not have risk factors for post‐partum haemorrhage were randomly assigned to receive either 8 L/min O2 via a face mask for 2 h (n = 214) or normally breathe room air after the delivery (n = 216). The oxygen was given to the women after delivering their babies. Active management of the third stage of labour was used in both groups. The primary outcome was mean blood loss during the third and fourth stages of labour.
Results:  No differences in demographic or clinical characteristics were observed between groups. The mean estimated blood loss at the third and fourth stages of labour did not significantly differ between the control and oxygen‐inhalation groups (294.5 ± 179.7 vs 273.4 ± 146.6 mL, respectively; P = 0.18). In addition, there was no significant difference in the proportion of women who experienced an estimated blood loss >500 mL or the percentage of women who needed additional uterotonic agents (11 [5.1%] vs 9 [4.2%], respectively; RR 1.2 95% CI 0.5–2.8; P = 0.82 and 12 [5.6%] vs 8 [3.7%], respectively; RR 1.4 95% CI 0.6–3.5; P = 0.49).
Conclusion:  Post‐partum oxygen inhalation is not beneficial for reducing vaginal blood loss during the third and fourth stages of labour.