The Effect of Inhaled Oxygen on Postpartum Hemorrhage: A Systematic Review and Meta-Analysis

Background: Postpartum Hemorrhage (PPH) is a significant problem that can increase the risk of maternal mortality. Previous studies investigated the effect of Inhaled Oxygen (IO) on PPH. They found some conflicting results. Thus, the current systematic review and meta-analysis aimed to determine the effect of IO on PPH. Materials and Methods: Randomized trials were searched according to the PRISMA framework until the end of November 2022 in Web of Science, PubMed, Scopus, and Cochrane Library databases. Statistical analyses were performed in the STATA v. 14 software. I2 statistic was applied to assess heterogeneity between studies. The random effect model, sample size, and mean and standard deviation of each group were applied to report the pooled effect size. Version 2 of the Cochrane risk-of-bias tool for randomized trials (RoB 2) was used to evaluate the risk of bias in the included studies. Finally, five articles were included in the meta-analysis. Two and three studies reported the mean of bleeding after vaginal delivery during one- and two-hours oxygen therapy, respectively. Results: Results showed that IO significantly reduced bleeding by 38.91 mL in the intervention group compared to routine care (WMD: −38.91, 95%CI: −60.18 to −17.64) after vaginal delivery. In addition, IO during one (WMD: −38.42, 95%CI: −71.62 to −5.22) and two (WMD: −41.93, 95%CI: −60.15 to − 23.71) hours significantly decreased bleeding in the intervention. Conclusion: According to the present study, IO can significantly reduce PPH in the intervention group compared to routine care. However, more rigorously randomized clinical trials are required to decide better about this issue.