A recent randomized trial published in the American Journal of Obstetrics and Gynecology unveiled that a higher dose of aspirin may reduce the risk of preeclampsia (PE) with severe features in high-risk obese pregnant women. Preeclampsia is characterized by high blood pressure and signs of damage to other organ systems, often affects the pregnant women. This in turn can lead to serious complications for both mother and baby. Preventive measures, including the use of low-dose aspirin, have been recommended to reduce these risks. However, recent data have raised concerns about the adequacy of the 81 mg dose, particularly in obese women, who may experience aspirin resistance by potentially diminishing the efficacy of drugs.

The study compared the efficacy of 162 mg of aspirin daily to the standard 81 mg dose, which is currently recommended by leading medical societies in the US for women at risk of PE. The study included a total of 220 participants between May 2019 and November 2022 with a body mass index (BMI) of 30 kg/m² or higher and at least one additional high-risk factor like a history of PE in a prior pregnancy, stage I hypertension, or diabetes diagnosed before 20 weeks of gestation.
The study wanted to evaluate whether the administration of 162 mg of aspirin would be more effective than 81 mg in reducing the incidence of PE with severe features. The participants were randomly assigned to one of the two aspirin dosage groups and were monitored from 12 to 20 weeks of gestation until delivery. The study excluded women with multifetal gestation, known major fetal anomalies, or existing conditions like seizure disorders or baseline proteinuria.

The results of this study showed that 35% of the women in the 162 mg group developed PE with severe features when compared to 40% in the 81 mg group. Although the difference was not statistically significant, the Bayesian analysis indicated a 78% probability that the higher dose would reduce the risk of severe PE. The best estimate suggests a 12% reduction in the incidence of PE with severe features when using 162 mg of aspirin compared to 81 mg.
Secondary outcomes, including rates of preterm birth due to preeclampsia, small for gestational age (SGA), placental abruption, and postpartum hemorrhage, were similar between the two groups. Adverse effects related to the medication were also comparable which indicated that the higher dose did not increase the risk of complications in the participants. Overall, the findings of this study highlight the potential benefits of a higher aspirin dose in preventing severe preeclampsia in high-risk obese women.
Reference:
Amro, F. H., Blackwell, S. C., Pedroza, C., Backley, S., Bitar, G., Daye, N., Bartal, M. F., Chauhan, S. P., & Sibai, B. M. (2024). Aspirin 162 mg versus 81 mg for Preeclampsia Prophylaxis in High-risk Obese Individuals: A Comparative Effectiveness Open Label Randomized Trial (ASPREO). In American Journal of Obstetrics and Gynecology. Elsevier BV. https://doi.org/10.1016/j.ajog.2024.06.038