Aspirin-related hemorrhagic complications in pregnancy: a nationwide French cohort study (ASPREG).

The increasingly wide use of low-dose aspirin during pregnancy to prevent preeclampsia, based on recently updated clinical guidelines, raises debates about potential maternal bleeding risks. This population-based study aimed to quantify the risk of hemorrhage complications associated with aspirin exposure. We performed a nationwide exposed/unexposed cohort study using the French National Health Data System (SNDS), analyzing 5,774,333 pregnancies between 2015 and 2022. Exposure was defined as a low-dose aspirin prescription (75-160 mg/day) during pregnancy (2.99% of the cohort). The primary endpoint was a hospital stay for maternal hemorrhage during the 1st, 2nd/3rd trimesters, or the postpartum period. Risk was evaluated using a Cox survival regression. Aspirin exposure was associated with a significantly increased risk of maternal hemorrhage: during the first trimester (Hazard Ratio [HR] 2.87 [95% CI 2.56-3.21]), the second and third trimesters (HR 1.74 [1.65-1.84]), and the post-partum (OR 1.44 [1.32-1.57]). The use of low-dose aspirin during pregnancy is associated with an increased risk of maternal bleeding events. These findings emphasize the need for a precise assessment of pregnant women who will really benefit from low-dose aspirin, to preserve its favorable benefits-risks balance.