(1186) Is low dose aspirin associated with bleeding complications in pregnancy?

Low dose aspirin (LDA) has been shown to reduce the risk for preterm pre-eclampsia. Some studies have reported an increased risk for bleeding complications in pregnancy.  Our aim was to evaluate the risk of abruption and postpartum hemorrhage (PPH) associated with LDA. 


Study Design:

This retrospective study included 73,694 births at 19 U.S. hospitals (01/2019-12/2021). Births were excluded if they were associated with multiple pregnancy (n=2209), placenta previa/accreta (n=380) or had missing data for LDA recommendation (n=590). Propensity scores were calculated using 19 features spanning sociodemographic factors, medical history, year of birth, and hospital providing care. The association between LDA and abruption or PPH was estimated by inverse probability weighting using the propensity scores.


Results:

We included 71,627 births in the final analysis; LDA was recommended to 6677 (9.3%). LDA was more likely to be recommended to older pregnant individuals, those with higher BMI, pre-existing medical complications, or giving birth at a level III hospital, and those who had an operative birth (cesarean or operative vaginal) (Table 1). Overall, 1,205 (1.7%) developed preterm preeclampsia: 1.3% in the no LDA and 5.7% in the LDA group. After inverse probability weighting with propensity scores, LDA was associated with increased risk of abruption (adjusted OR 1.53; 95% CI 1.37 – 1.71) and PPH (adjusted OR 1.21; 95% CI, 1.16– 1.26).


Conclusion:

LDA was associated with increased risk for abruption and with PPH. Limitations of the study include the lack of data on aspirin dose and timing in pregnancy, as well as the possibility of unaccounted confounding. However, our results support the need for more research into LDA and bleeding complications in pregnancy before recommending LDA beyond the highest risk pregnancies.