Is it safe to take two low‑dose aspirin (81 mg) tablets during pregnancy?

Low-Dose Aspirin During Pregnancy: Safety of Two 81mg Tablets

Taking two baby aspirins (162 mg total) during pregnancy is safe and may actually be more effective than the standard single 81 mg dose for preventing preeclampsia in high-risk women, with no increase in bleeding complications. However, current guidelines still recommend only 81 mg daily, so the higher dose should be discussed with your obstetrician.

Current Guideline Recommendations

The ACOG (American College of Obstetricians and Gynecologists) endorsed the USPSTF recommendation in 2016 for 81 mg low-dose aspirin for patients with high-risk factors between 12 and 28 weeks of gestation 1. Multiple international guidelines recommend similar dosing:

• ACOG: 60-80 mg/day starting late first trimester 2
• WHO: 75 mg/day starting 12-20 weeks 2
• NICE (UK): 75-150 mg/day from 12 weeks 2
• American Academy of Family Physicians: 81 mg/day after 12 weeks 2

The USPSTF found that low-dose aspirin (60-150 mg/day range) reduced preeclampsia risk by 24%, preterm birth by 14%, and intrauterine growth restriction by 20% in high-risk women 2.

Safety Profile: No Increased Bleeding Risk

The evidence strongly supports that low-dose aspirin does not increase serious bleeding complications during pregnancy. The USPSTF found adequate evidence that low-dose aspirin does not increase risk for:

• Placental abruption
• Postpartum hemorrhage
• Fetal intracranial bleeding
• Perinatal mortality 2

The FDA label cautions about aspirin use in the last 3 months of pregnancy unless directed by a doctor 3, but this warning predates the robust evidence supporting low-dose aspirin for preeclampsia prevention.

Emerging Evidence on Higher Dosing (162 mg)

Recent research suggests 162 mg may be superior to 81 mg, particularly in high-risk populations:

Key Studies:

Most Recent High-Quality Evidence (2025): A randomized trial in obese high-risk women found that 162 mg aspirin had a 78% probability of reducing preeclampsia with severe features compared to 81 mg (35% vs 40% incidence). Importantly, bleeding complications were identical between groups 4.

Retrospective Cohort (2024): Among 3,597 high-risk patients, the preeclampsia rate was significantly lower with 162 mg (10.1%) versus 81 mg (14.2%), with no increase in postpartum hemorrhage, hematoma, or neonatal bleeding 5.

Meta-analysis (2023): Pooled analysis of 4 RCTs (552 participants) showed 150-162 mg aspirin reduced preterm preeclampsia by 66% compared to 75-81 mg (RR 0.34,95% CI 0.15-0.79) when started in the first trimester 6.

Important Caveat:

Despite this emerging evidence, current official guidelines have not yet been updated to recommend 162 mg 7, 8. The studies are relatively small and more large-scale trials are needed.

Who Should Take Low-Dose Aspirin?

High-risk factors (one or more warrants aspirin) 2:

• History of preeclampsia (especially early-onset <34 weeks)
• Chronic hypertension
• Type 1 or 2 diabetes
• Renal disease
• Autoimmune disease (lupus, antiphospholipid syndrome)
• Multifetal gestation

Moderate-risk factors (multiple factors may warrant aspirin):

• First pregnancy
• Age ≥40 years
• BMI ≥35 kg/m²
• Family history of preeclampsia
• Pregnancy interval >10 years

Timing Matters

Start between 12-16 weeks of gestation for optimal effectiveness 1. Evidence suggests:

• Starting before 16 weeks is most effective 8
• Doses >100 mg initiated before 16 weeks show greatest benefit 8
• Continue until delivery 1, 2

Recent safety data shows no increase in adverse events when starting before 11 weeks, including no increase in congenital anomalies 9.

Practical Recommendation Algorithm

For standard-risk pregnant women: No aspirin needed

For high-risk women (see criteria above):

1. Standard approach: 81 mg daily starting 12-16 weeks until delivery (current guideline-concordant) 1
2. Consider 162 mg if:
   • Obese (BMI ≥30) with high-risk factors 4
   • Multiple high-risk factors present 5
   • History of severe early-onset preeclampsia
   • Discuss with your obstetrician as this exceeds current formal guidelines

Contraindications to aspirin:

• Aspirin allergy
• Active bleeding disorder
• Severe thrombocytopenia
• History of aspirin-induced complications

Bottom Line

Two baby aspirins (162 mg) during pregnancy appears safe with no increased bleeding risk and may offer superior preeclampsia prevention compared to one tablet (81 mg). However, since 81 mg remains the official guideline recommendation, discuss the higher dose with your obstetrician if you have multiple high-risk factors or obesity. The safety profile of low-dose aspirin in pregnancy is well-established, with substantial benefits for reducing serious pregnancy complications in at-risk women 2.