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Poster Session 2

(420) Maternal placental vascular pathology association with aspirin response among high-risk singleton pregnancies

Thursday, January 30, 2025
4:00 PM – 6:00 PM  
Objective: Placental vascular pathologies are noted in pregnancies complicated by preeclampsia and preterm birth.  Aspirin initiation in high-risk pregnancies reduces the risk of these outcomes. However, it is unclear how aspirin response affects placental histopathology. Our objective is to evaluate the relationship between aspirin response and placental vascular pathology in high-risk pregnancies taking 81mg aspirin daily.

Study Design: This is a secondary analysis of a prospective cohort of high-risk singletons taking aspirin daily. Placental maternal vascular pathology was categorized according to Amsterdam classification system. The primary outcome was maternal vascular malperfusion (MVM). Aspirin response was assessed by Platelet Function Assay-100 epinephrine closure time (PFA-100) at baseline (before aspirin, < 16 weeks), 2-4 weeks after aspirin initiation (follow up-1), and at 28-32 weeks gestation (follow up-2). The exposure was PFA-100 assessed as a continuous and categorical variable (<150 seconds, inadequate response) in those with and without placental MVM. The Mann-Whitney-U test and Chi-squared test were used.

Results: Of the original cohort (n=130), 91 participants took 81mg aspirin daily, completed requisite follow-up, and had placental histopathology available. 38 (42%) exhibited placental MVM; baseline characteristics were similar in those with and without MVM (Table 1). There was no significant difference in aspirin response in those with and without placental MVM (Table 2), although there was a higher rate of inadequate aspirin response at 28-32 weeks in those who developed MVM. However, this was not statistically significant (p=0.14).

Conclusion: We found a high rate of placental MVM in high-risk singletons taking aspirin daily, and a strong association between placental MVM and preterm birth. We did not find a significant association between aspirin response and placental MVM, although a larger study should be done to evaluate the relationship between aspirin response and placental vascular pathology especially when assessed in the 3rd trimester.