Hypertensive disorders of pregnancy—including preeclampsia, gestational hypertension, and eclampsia—are a leading cause of maternal and perinatal morbidity and mortality worldwide. In the United States, preeclampsia contributes to 15% of maternal deaths and increases the risk of preterm birth, fetal growth restriction, and stillbirth. But there’s good news: one of the most effective, affordable, and accessible preventive tools is already on pharmacy shelves—low-dose aspirin.
This blog post explores the science, guidelines, and clinical implementation of low-dose aspirin in pregnancy. We will discuss how this simple step can help prevent these complications.
The Problem: Hypertensive Disorders of Pregnancy
Hypertensive disorders affect 5–10% of pregnancies, with preeclampsia being one of the most severe forms. It typically occurs after 20 weeks of gestation and can lead to:
- Organ dysfunction (kidney, liver, brain)
- Placental abruption
- Intrauterine growth restriction (IUGR)
- Preterm birth
- Maternal seizures (eclampsia)
- Fetal demise
While preeclampsia is not fully preventable, we can significantly reduce its incidence and severity in high-risk patients through prophylactic low-dose aspirin therapy. For more information on maternal health, you can visit the World Health Organization (WHO) website.
The Solution: Low-Dose Aspirin (LDA)
What It Is
Low-dose aspirin refers to 81–150 mg of aspirin taken once daily, typically starting in the late first trimester or early second trimester.
How It Works
Aspirin inhibits platelet aggregation and thromboxane production, which improves uteroplacental blood flow and reduces inflammation. These mechanisms are implicated in the development of preeclampsia.
The Evidence
The United States Preventive Services Task Force (USPSTF) recommends 81 mg daily starting between 12–28 weeks (ideally before 16 weeks) in those at risk for preeclampsia. The 2017 ASPRE trial found that 150 mg daily of aspirin starting at 11–14 weeks reduced the risk of preterm preeclampsia by over 60% in high-risk women.
Who Should Take Low-Dose Aspirin?
High-Risk Indications (1 or more of the following):
- History of preeclampsia (especially early onset or with adverse outcome)
- Multifetal gestation (twins or more)
- Chronic hypertension
- Type 1 or 2 diabetes
- Renal disease
- Autoimmune diseases (e.g., lupus, antiphospholipid syndrome)
Moderate-Risk Factors (2 or more of the following):
- Nulliparity
- Obesity (BMI ≥30)
- African American race
- Family history of preeclampsia
- Maternal age ≥35
- Socioeconomic factors (low income, poor access to prenatal care)
It is recommended to initiate Low-Dose Aspirin at 12–16 weeks and continue through delivery unless contraindicated.
Safety and Implementation of Low-Dose Aspirin
Safety Profile
Low-dose aspirin is safe for both mother and fetus when taken as prescribed:
- No increased risk of postpartum hemorrhage
- No evidence of teratogenicity
- No adverse effect on fetal development
- Can be continued until delivery, in most cases
Contraindications include aspirin allergy, bleeding disorders, or gastrointestinal ulcers.
Implementation in Practice
Best Practices:
- Screen all patients at the first prenatal visit for aspirin eligibility.
- Use checklists or electronic health record prompts to flag candidates.
- Educate patients on why aspirin is important and how to take it.
- Coordinate with pharmacy and nursing to ensure consistent messaging.
Public Health Impact of Low-Dose Aspirin in Pregnancy
If implemented widely and early, low-dose aspirin could prevent tens of thousands of cases of preeclampsia and related complications annually in the U.S. alone. For high-risk groups, especially Black women, who face disproportionately higher rates of preeclampsia and maternal mortality, Low-Dose Aspirin represents a powerful tool for health equity.
For more information about maternal health and equity, you can visit the Centers for Disease Control and Prevention (CDC) website. You can also learn more about other health topics by checking out our other blog posts, like this one on managing gestational diabetes.
Final Thoughts on Low-Dose Aspirin in Pregnancy
Low-dose aspirin is simple, safe, and cost-effective—yet underutilized in many clinical settings. Every prenatal care provider should incorporate early risk screening and Low-Dose Aspirin initiation into routine care.
When it comes to hypertensive disorders of pregnancy, prevention is better than reaction—and low-dose aspirin is one of the best preventive tools we have.
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Maternal 911 Education Systems, LLC includes an obstetrician-gynecologist and women’s healthcare nurse practitioner with a focus on emergency obstetrics, intrapartum, and postpartum safety. Passionate about maternal health education, Maternal 911 advocates for evidence-based practices and interdisciplinary team training.
