Low-Dose Aspirin in Pregnancy: Who It's For and Why
Low-dose aspirin — sometimes called "baby aspirin" — is one of the few medications in pregnancy with a specific, evidence-based preventive use: lowering the risk of preeclampsia in people who qualify for it. It's also one of the more commonly misunderstood, since it sits right next to a list of pain relievers that are generally avoided in pregnancy. Here's the actual distinction.
Last updated August 2026
Who it's actually for
Your provider screens for this using a standard set of risk factors, not a self-diagnosis checklist. One higher-risk factor — a prior pregnancy with preeclampsia, carrying multiples, chronic hypertension, type 1 or type 2 diabetes that predates the pregnancy, kidney disease, or an autoimmune condition like lupus or antiphospholipid syndrome — is generally enough on its own. Two or more moderate-risk factors together (a first pregnancy, obesity, a family history of preeclampsia, being 35 or older, and a few other personal-history factors) can also qualify. This is a conversation your provider should be having with you based on your actual history, not something to work out alone.
The dose and timing
The standard recommendation is 81mg once daily — the same dose sold over the counter as "low-dose" or "baby" aspirin. It's ideally started between 12 and 16 weeks, and generally not started for the first time after 28 weeks, since the preventive effect depends on early, sustained use rather than starting late. Most people continue it daily through delivery, though the exact stop point is worth confirming with your provider rather than assuming.
Why this is different from taking ibuprofen for a headache
Pain-relief-dose NSAIDs — ibuprofen, naproxen, and aspirin at regular pain-relief doses — are generally avoided in pregnancy, especially after 20 weeks, because of real risks to fetal kidney function and blood flow. Low-dose aspirin for preeclampsia prevention works differently: at 81mg, it shifts the balance between two substances (thromboxane and prostacyclin) in a way that specifically supports healthy blood flow to the placenta, rather than acting as a general pain reliever. Same drug, genuinely different dose and purpose — this is why a prescribed low-dose regimen and a bottle of regular-strength aspirin aren't interchangeable, and why "aspirin is generally avoided in pregnancy" and "take this specific low dose daily" aren't actually a contradiction.
What it actually reduces
For people who qualify based on risk factors, daily low-dose aspirin meaningfully reduces the chance of developing preeclampsia. It's a real preventive measure, not a guarantee — it lowers risk, it doesn't eliminate it — which is part of why ongoing monitoring (blood pressure checks, watching for symptoms) still matters throughout pregnancy even while taking it.
Safety
At the 81mg dose used for this purpose, aspirin is well-studied in pregnancy and considered safe for both the pregnant person and the baby when taken as recommended. It's not the same safety profile as high-dose aspirin or other NSAIDs. Most people don't need to stop it in the days immediately before a planned delivery, but the exact timing near the end of pregnancy — especially around a scheduled induction or C-section — is worth a specific conversation with your provider rather than stopping on your own.
Worth discussing with your provider
Educational information only — general patterns that vary by person. This is not medical advice, a diagnosis, or a substitute for care from your own clinician.
More from Education