Preeclampsia Prevention with Low-Dose Aspirin

Risk Assessment and Benefit

• Low-dose aspirin reduces the risk of preeclampsia by 24% in women at increased risk, with an absolute risk reduction ranging from 2% to 5% 1, 2
• The number needed to treat to prevent one case of preeclampsia is 42 in women at increased risk 3

Dosage and Timing Considerations

• The most commonly studied dosages are 60 mg/day and 100 mg/day, with 81 mg/day being a reasonable dosage in the United States 4
• Low-dose aspirin should be initiated between 12 and 16 weeks of gestation for optimal effect 5
• There is no evidence of additional benefit when starting aspirin earlier than 16 weeks compared to later initiation 6

Safety Profile

• Low-dose aspirin does not increase the risk of placental abruption, postpartum hemorrhage, fetal intracranial bleeding, or perinatal mortality 3
• No significant differences were found in cesarean delivery rates between aspirin and placebo groups 2

Additional Benefits

• Low-dose aspirin provides a 14% reduction in risk of preterm birth 1, 2
• Low-dose aspirin provides a 20% reduction in risk of intrauterine growth restriction (IUGR) 1, 2
• Low-dose aspirin increases mean birthweight by approximately 130g 2

Prevention of Preeclampsia with Low-Dose Aspirin

Indications for Aspirin Prophylaxis

• History of preeclampsia is considered a high-risk factor that warrants prophylactic aspirin therapy in subsequent pregnancies, as recommended by the World Health Organization 7
• Women with both chronic hypertension and history of preeclampsia have a significantly higher risk of developing superimposed preeclampsia in subsequent pregnancies (45.7% vs. 30.1% in those with chronic hypertension alone) 8

Guideline Recommendations

• The U.S. Preventive Services Task Force recommends low-dose aspirin for women at high risk of preeclampsia, including those with a history of preeclampsia 9, 10
• The American Heart Association and American Stroke Association recommend low-dose aspirin for women with previous pregnancy-related hypertension 7