Low-dose aspirin is the only pharmacological intervention with consistent evidence of reducing the risk of preeclampsia in high-risk pregnancies, but there is considerable variability in the response of individual women to this treatment. The researchers looked at various biomarkers—genetic variants related to aspirin metabolism, platelet function tests, and angiogenic biomarkers (such as soluble fms-like tyrosine kinase-1 and placental growth factor)—to better understand which women would benefit from the treatment. Although these biomarkers provide important insight into the biological mechanisms of preeclampsia, most of the evidence comes from observational studies without randomized trials to support their practical use. Genetic testing and platelet function tests lack standardized thresholds and validation in pregnant women. Angiogenic biomarkers have a proven role in diagnosis later in pregnancy, but their use to inform decisions about aspirin therapy in the first trimester remains experimental. Until further randomized trials are conducted, aspirin prophylaxis should continue to be guided by standard risk assessment according to clinical guidelines, with biomarker-based approaches reserved for future research.