Abstract
Objective This study aimed to investigate whether aspirin 81 mg daily for preeclampsia prevention
is associated with increased risk of postpartum blood loss at the time of delivery.
Study Design This is a retrospective cohort study performed at a tertiary hospital from January
2018 to April 2021. Data were extracted from the electronic medical record. Patients
prescribed low-dose aspirin (LDA) were compared with patients who were not. The primary
outcome was a composite of postpartum blood loss, defined as: estimated blood loss
(EBL) >1,000 mL, documentation of International Classification of Diseases-9/-10 codes
for postpartum hemorrhage (PPH), or red blood cell (RBC) transfusion. Bivariate analysis,
and unadjusted and adjusted logistic regression modeling were performed.
Results Among 16,980 deliveries, 1,922 (11.3%) were prescribed LDA. Patients prescribed LDA
were more likely to be >35 years old, nulliparous, obese, taking other anticoagulants,
or have diagnoses of diabetes, systemic lupus erythematosus, fibroids, or hypertensive
disease of pregnancy. After adjusting for potential confounders, the significant association
between LDA use and the composite did not persist (adjusted odds ratio [aOR]: 1.1,
95% confidence interval [CI]: 1.0–1.3) nor did the association between EBL > 1,000 mL
(aOR: 1.0, 95% CI: 0.9–1.3) and RBC transfusion (aOR: 1.3, 95% CI: 0.9–1.7). The association
between LDA and PPH remained significant (aOR: 1.3, 95% CI: 1.1–1.6). Patients who
discontinued LDA <7 days prior to delivery had an increased risk of the postpartum
blood loss composite compared discontinuation ≥7 days (15.0 vs. 9.3%; p = 0.03).
Conclusion There may be an association between LDA use and increased risk of postpartum bleeding.
This suggests that use of LDA outside the recommended guidelines should be cautioned
and further investigation is needed to determine its ideal dosing and timing of discontinuation.
Key Points
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There may be an association with LDA and an increased risk of postpartum bleeding.
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Patients who discontinued LDA less than 7 days prior to delivery had an increased
rate of postpartum bleeding.
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Additional research is need to determine optimal LDA dose and timing of discontinuation.
Keywords
postpartum hemorrhage - blood transfusion - preeclampsia prophylaxis - postpartum
blood loss
