Do I start Aspirin (Acetylsalicylic Acid) for gestational hypertension?

Aspirin for Gestational Hypertension: Evidence-Based Recommendations

Low-dose aspirin is not recommended for women with gestational hypertension alone, as current evidence does not support its use in this specific condition. 1, 2, 3

Understanding the Evidence

The recommendation regarding aspirin use in pregnancy is based on risk stratification for developing preeclampsia, not for treatment of gestational hypertension that has already developed.

Risk Factors for Preeclampsia

High-Risk Factors:

• History of preeclampsia
• Multifetal gestation
• Chronic hypertension
• Type 1 or 2 diabetes
• Renal disease
• Autoimmune disease (such as lupus or antiphospholipid syndrome)

Moderate-Risk Factors:

• First pregnancy (nulliparity)
• Maternal age ≥35 years
• BMI >30
• Family history of preeclampsia
• Sociodemographic characteristics
• Personal history factors

Current Guidelines

ACOG and the Society for Maternal-Fetal Medicine recommend low-dose aspirin (81 mg/day) only for:

• Women with high-risk factors for preeclampsia
• Women with more than one moderate risk factor 2, 3

Importantly, gestational hypertension alone (without other risk factors) is not listed as an indication for aspirin prophylaxis.

Timing and Dosage

If aspirin is indicated based on risk factors (not gestational hypertension alone):

• Initiation: Between 12-28 weeks gestation (optimally before 16 weeks) 1, 2
• Dosage: Varies by guideline:
  • 81 mg daily (USA guidelines) 2, 3
  • 75-162 mg (Canadian and ISSHP guidelines) 1
  • Higher doses (150 mg) may be considered in some cases 1
• Duration: Continue until delivery 1, 2

Safety Considerations

The FDA label for aspirin warns that it should be used with caution during pregnancy, especially during the last trimester, as it may cause problems in the unborn child or complications during delivery 4. However, low-dose aspirin (81 mg) is generally considered safe when used for appropriate indications.

Research Findings

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 1. This suggests that even in high-risk populations, the benefits may be limited.

Clinical Decision Algorithm

1. Determine if the patient has gestational hypertension only or other risk factors:

   • If gestational hypertension only → No aspirin recommended
   • If gestational hypertension plus other high-risk factors → Consider aspirin

2. If aspirin is indicated based on risk factors:

   • Start at 12-16 weeks gestation (if possible)
   • Use 81 mg daily
   • Continue until delivery
   • Monitor for any bleeding complications

Common Pitfalls to Avoid

• Starting aspirin too late in pregnancy (after 16 weeks) may reduce its effectiveness
• Confusing gestational hypertension (which develops after 20 weeks without proteinuria) with chronic hypertension (present before pregnancy or before 20 weeks)
• Using aspirin without proper risk stratification
• Continuing aspirin use without monitoring for potential adverse effects

In conclusion, gestational hypertension alone is not an indication for starting aspirin therapy. Aspirin should be reserved for women with high-risk factors for preeclampsia or multiple moderate risk factors, and ideally started before 16 weeks of gestation.