Evaluation of Low-Dose Aspirin on Pregnancy Outcomes: A Systematic Review and Meta-analysis.

Background: Preeclampsia is a severe pregnancy disorder linked to high maternal and neonatal mortality. This meta-analysis evaluates the effectiveness of low-dose aspirin in reducing the occurrence of preeclampsia and associated outcomes.

Methods: A total of 28 trials were included, analyzed using a random-effects model to calculate risk ratios (RR) and 95% confidence intervals (CI). The studies compared low-dose aspirin administered at or before 16 weeks of gestation to a control group. The measured parameters are the effect of low-dose aspirin on pregnancy outcomes. Study inclusion criteria consisted of studies in which low-dose aspirin was administrated at or before 16 weeks of gestation and compared to a control group.

Results: Low-dose aspirin significantly reduced preterm (RR=0.52, 95% CI [0.31, 0.88]) and term preeclampsia (RR=0.97, 95% CI [0.69, 1.38]). It also decreased intrauterine growth restriction (RR=0.63, 95% CI [0.54, 0.74]). However, no significant differences were observed for postpartum hemorrhage (RR=0.71, 95% CI [0.49, 1.02]) or gestational hypertension (RR=0.65, 95% CI [0.39, 1.07]). Aspirin doses≥100 mg were more effective in reducing preterm preeclampsia risk compared to doses<100 mg, which showed variable efficacy and greater heterogeneity.

Conclusion: Low-dose aspirin significantly decreases the risk of preterm and term preeclampsia but has limited impact on gestational hypertension and postpartum bleeding. Study limitations include the absence of large randomized controlled trials (RCTs) early in pregnancy (before 16 weeks) and small sample sizes in the included trials, complicating precise dose determination.