Is aspirin safe during pregnancy?
Answer
Full-dose aspirin (325 mg) is not recommended in pregnancy — same NSAID risks as ibuprofen. Low-dose aspirin (81 mg) is sometimes prescribed by OBs for preeclampsia prevention in high-risk pregnancies — that's a separate clinical scenario.
Two different aspirin scenarios
Aspirin in pregnancy is a tale of two doses:
- Full-dose aspirin (325 mg, OTC pain relief): Not recommended. Shares all NSAID risks of ibuprofen plus additional bleeding concerns.
- Low-dose aspirin (81 mg, “baby aspirin”): Prescribed by OBs for preeclampsia prevention in high-risk pregnancies. Different clinical scenario; do NOT discontinue without consulting your prescriber.
Why full-dose aspirin is avoided
Full-dose aspirin (325 mg or higher) is in the same drug class as [ibuprofen](/ingredients/ibuprofen/) — nonsteroidal anti-inflammatory drugs (NSAIDs). It shares the same pregnancy concerns:
- Fetal kidney effects after 20 weeks — NSAID-induced reduction in fetal urine output, oligohydramnios1
- Premature closure of ductus arteriosus after 30 weeks — serious neonatal complication
- Bleeding risk — aspirin specifically inhibits platelet function more than other NSAIDs, raising maternal hemorrhage risk in delivery
- Reye syndrome concerns — less relevant in adults but bear noting
The October 2020 FDA NSAID warning specifically named aspirin among the drugs to avoid at 20 weeks and beyond2.
Low-dose aspirin (81 mg): the exception
Low-dose aspirin (also called “baby aspirin,” typically 81 mg/day) is prescribed by obstetricians for two main indications during pregnancy:
- Preeclampsia prevention — recommended by ACOG for patients with high preeclampsia risk (chronic hypertension, prior preeclampsia, multiple gestation, autoimmune conditions, etc.), starting between 12–28 weeks and continuing until delivery3
- Antiphospholipid syndrome (APS) — in combination with heparin, low-dose aspirin reduces miscarriage rates in patients with APS
The evidence base for low-dose aspirin in these indications is strong. The risk of fetal harm at 81 mg/day is minimal compared to the benefit of preventing severe preeclampsia (a leading cause of maternal and neonatal morbidity).
If your OB prescribed low-dose aspirin: continue taking it as directed. Do not stop based on general “avoid NSAIDs” guidance. The clinical context matters.
What to take instead for headache or pain
For OTC pain relief in pregnancy: [acetaminophen (Tylenol)](/ingredients/acetaminophen/) is the first-line choice. Avoid:
- Aspirin (Bayer, Bufferin, Anacin)
- Ibuprofen (Advil, Motrin)
- Naproxen (Aleve)
- Excedrin Migraine (contains aspirin AND caffeine)
What about Bismuth Subsalicylate (Pepto-Bismol)?
Pepto-Bismol contains a salicylate (related to aspirin chemistry) and is not recommended in pregnancy for the same NSAID-class reasons4. For pregnancy-related upset stomach, calcium carbonate (Tums) is the safer first choice; for diarrhea, hydration and BRAT diet rather than OTC antidiarrheals.
Related ingredients
Ibuprofen
Avoid ibuprofen after 20 weeks of pregnancy. NSAIDs can cause fetal kidney problems, oligohydramnios, and (after 30 weeks) premature closure of the…
Acetaminophen
Acetaminophen (Tylenol) is the first-line OTC pain reliever and fever reducer in pregnancy per ACOG. Considered safe at recommended doses across all…
Sources
- Bloor M, Paech M. (2013). Nonsteroidal anti-inflammatory drugs during pregnancy and the initiation of lactation. Anesthesia & Analgesia. View source →
- U.S. Food and Drug Administration. (2020). FDA recommends avoiding NSAIDs in pregnancy at 20 weeks or later. FDA. View source →
- American College of Obstetricians and Gynecologists. (2018). ACOG Committee Opinion 743: Low-dose aspirin use during pregnancy. ACOG. View source →
- Briggs GG, Freeman RK. (2014). Drugs in Pregnancy and Lactation, 10th ed. Lippincott Williams & Wilkins. View source →