Low-dose asprin use during pregnancy may be a potential risk for postpartum hemorrhage and increased blood loss: a systematic review and meta-analysis

The association between aspirin use during pregnancy and the risk of postpartum hemorrhage remains unclear. This study aimed to explore the incidence of postpartum hemorrhage and the amount of postpartum blood loss among women who used aspirin during pregnancy.From inception to October 2022, this study searched the following databases: MEDLINE, Web of Science, Embase, and the Cochrane Central Register of Controlled Trials.Studies comparing pregnancy outcomes that covered the incidence of postpartum hemorrhage or the amount of postpartum blood loss in pregnancies with aspirin vs placebo (or no aspirin) were included.Reviewers separately ascertained studies, obtained data, and gauged study quality. The meta-analysis was conducted using a random effects model owing to the probable heterogeneity of the included studies. The rates of postpartum hemorrhage or the mean amounts of postpartum blood loss were compared, and the odds ratios or mean differences with 95% confidence intervals were estimated. Of note, 2 parts performed both a pooled analysis of randomized controlled trials and cohort studies and a separate analysis of randomized controlled trials.Overall, 21 studies with 373,926 women were included in the postpartum hemorrhage part, and 7 studies with 10,163 women were included in the postpartum blood loss part. The results suggested that aspirin (dose 60-150mg a day) use during pregnancy was associated with an increased incidence of postpartum hemorrhage (odds ratio, 1.20; 95% confidence interval, 1.07-1.34). When only randomized controlled trials were retained, the results remained significant (odds ratio, 1.12; 95% confidence interval, 1.00-1.25). In the second part, higher total blood loss after delivery was obtained (mean difference, 12.85 mL; 95% confidence interval, 3.28-22.42), and the result was unaltered when cohort studies were eliminated (mean difference, 13.72 mL; 95% confidence interval, 4.63-22.81). The conclusions are more likely to be obtained in developed countries.Low-dose aspirin use during pregnancy is a potential risk of postpartum hemorrhage and does slightly increase the amount of postpartum blood loss. Without denying the combined value of aspirin, our conclusions raised an alarm for clinicians about postpartum hemorrhage in women using aspirin during pregnancy.