The role of aspirin dose and initiation time in the prevention of preeclampsia and corresponding complications: a meta-analysis of RCTs

Purpose To investigate the role of different dosages and initial times of aspirin in preeclampsia prevention. Methods This meta-analysis was performed based on randomized-control trials (RCTs). RCTs of women assigned to receive low-dose aspirin, placebo, or no treatment were included. Preeclampsia and corresponding complications were pooled for analysis. All studies were retrieved from PubMed, Embase, Cochrane and Web of Science. Results A total of 46 studies were obtained in this meta-analysis, which consisted of 24,028 participants. When women at <= 16 gestational weeks started treatment with a dosage of < 100 mg/day aspirin, there was a significant reduction in the incidence of preeclampsia (RR = 0.75; 95% CI 0.58-0.98; P = 0.03), while in the subgroup receiving >= 100 mg/day aspirin, the result was RR = 0.71 (95% CI 0.53-0.95; P = 0.02). When aspirin was initiated at > 16 weeks, with a dosage of < 100 mg/day aspirin, there was a lesser preventive effect (RR = 0.80; 95% Cl 0.64-1.00; P = 0.05), and there was no significance in the subgroup receiving >= 100 mg/day aspirin (RR = 0.76; 95% Cl 0.45-1.31; P = 0.32). Furthermore, aspirin was revealed to have a protective effect on reducing preterm delivery, but there was an increased risk of postpartum hemorrhage. No significant result was obtained for fetal loss. Conclusion The results of this meta-analysis suggest that high-risk pregnant women can prevent preeclampsia or preterm delivery by taking low-dose aspirin; the most efficient period is <= 16 weeks of gestation, and the best dose is >= 100 mg.