ASA and Preeclampsia

Q: Which Aspirin is recommended in high to moderate-risk preeclampsia? (select one)

A) low dose

B) high dose

Answer: A

Low-dose aspirin (ASA) is found to reduce the frequency of preeclampsia and many adverse pregnancy outcomes, such as preterm birth and growth restriction, by 10-20% when taken by patients at moderate to high risk of the disease. Low-dose ASA has an excellent maternal/fetal safety profile. 

Aspirin is recommended on the assumption that preeclampsia is associated with increased platelet turnover and increased platelet-derived thromboxane levels.

It should be noted that as opposed to high-dose aspirin therapy, low-dose aspirin (up to 150 mg/day) diminishes platelet thromboxane synthesis while maintaining vascular wall prostacyclin synthesis. Thromboxane promotes platelet aggregation and arterial constriction, whereas prostacyclin inhibits platelet aggregation and promotes vasodilatation. It also helps by modulating inflammation, which is exaggerated in patients with preeclampsia.

The American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine support the USPSTF guideline criteria for the prevention of preeclampsia. Low-dose aspirin (81 mg/day) prophylaxis is recommended in women at high risk of preeclampsia and should be initiated between 12 weeks and 28 weeks of gestation (optimally before 16 weeks) and continued daily until delivery. Women receiving medically indicated low-dose aspirin for other established medical indications before 12–28 weeks may continue with low-dose aspirin treatment. 

High-dose ASA does not provide any added benefit but increases the rate of bleeding and related complications.

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References:

1. Dekker GA, Sibai BM. Low-dose aspirin in the prevention of preeclampsia and fetal growth retardation: rationale, mechanisms, and clinical trials. Am J Obstet Gynecol 1993; 168:214.

2. Cadavid AP. Aspirin: The Mechanism of Action Revisited in the Context of Pregnancy Complications. Front Immunol 2017; 8:261.