Aspirin Use in Pregnancy

Introduction to Aspirin Therapy

The American College of Obstetricians and Gynecologists (ACOG) recommends against the use of low-dose aspirin for women with gestational hypertension alone, as current evidence does not support its use in this specific condition 1

Women with high-risk factors for preeclampsia, such as a history of preeclampsia, multifetal gestation, chronic hypertension, type 1 or 2 diabetes, renal disease, or autoimmune disease, may benefit from low-dose aspirin therapy 1
Women with more than one moderate risk factor, including nulliparity, maternal age ≥35 years, BMI >30, family history of preeclampsia, or sociodemographic characteristics, may also benefit from low-dose aspirin therapy 2

The recommended dosage of aspirin varies by guideline, with the USA guidelines recommending 81 mg daily, and the Canadian and ISSHP guidelines recommending 75-162 mg daily 2
Higher doses of aspirin (150 mg) may be considered in some cases, but the benefits and risks must be carefully weighed 1
Aspirin therapy should be initiated between 12-28 weeks gestation, optimally before 16 weeks, and continued until delivery 2

Low-dose aspirin (81 mg) is generally considered safe when used for appropriate indications, but may cause problems in the unborn child or complications during delivery, especially during the last trimester 1
A 2020 study found that low-dose aspirin (81 mg) initiated between 12-16 weeks of gestation did not decrease the incidence of superimposed preeclampsia, severe features, small for gestational age, or preterm birth in patients with chronic hypertension, suggesting that the benefits may be limited 1

Starting aspirin too late in pregnancy (after 16 weeks) may reduce its effectiveness, and confusing gestational hypertension with chronic hypertension can lead to inappropriate use of aspirin therapy 2
Aspirin therapy should be used with caution and monitored for potential adverse effects, such as bleeding complications 2