Optimal Aspirin Dosage for the Prevention of Preeclampsia and Other Adverse Pregnancy Outcomes : A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background/Objectives: This systematic review and meta-analysis aimed to determine the effectiveness of different aspirin dosages in preventing preeclampsia and its effect on other pregnancy-associated conditions. Methods: A comprehensive search of three databases (Pubmed, Embase, and Cochrane Library) was conducted for randomized controlled trials without time interval criteria, comparing aspirin at various doses with placebo or no specific preeclampsia prophylaxis. Eligible randomized controlled trials (RCTs) examined pregnant women receiving aspirin at any dose and time during their pregnancy, while the control group received a placebo, or placebo and a different dose of aspirin, or no specific preeclampsia prevention. No exclusion criteria were established regarding the population, study size, study site, or length of aspirin prophylaxis. Studies examining additional preventive medication (such as low-molecular-weight heparin) compared to aspirin without a placebo group were excluded. For all outcomes, the risk ratios (RRs) and mean differences (MDs) with 95% confidence intervals (CIs) were calculated. Meta-regression was performed to examine the relation between aspirin dosage and preeclampsia. Results: Based on the analysis of 31 studies involving 28,318 pregnancies and 20 studies involving 26,551 pregnancies, the early initiation of aspirin significantly reduced the overall incidence of preeclampsia (RR = 0.63, CI: 0.47-0.84) and perinatal death risk (RR = 0.82, CI: 0.72-0.93), respectively. Based on our meta-regression model, we could not establish a dose-dependent correlation between aspirin dosage and the risk of preeclampsia. Conclusions: Early-initiated aspirin prophylaxis is effective in preventing preeclampsia, without raising the incidence of placental abruption or increasing the amount of peripartum bleeding. No specific dose was superior to others; thus, further research should explore higher doses and focus on preterm preeclampsia, maternal-fetal complications, and bleeding.