Does Low-dose Aspirin prevent preeclampsia or merely delay it?

Though low-dose aspirin (LDA) has increasingly been broadly implemented into clinical practice for the prevention of preeclampsia and other adverse pregnancy outcomes, its impact on reducing the overall rate of preeclampsia has been modest (10-20% decrease). When examined more closely, the clinical impact of LDA may actually be to the apparent delay of early onset preeclampsia before 34 weeks (EOPE). The findings may be the result of both pre-eclampsia and pre-term pre-eclampsia being a common phenotype of differing disease processes that are responsive to aspirin. Given that EOPE drives the majority of maternal and fetal/neonatal morbidity and mortality, such prevention may confer outsized long-term benefits for both mother and child.