Does Baby Aspirin Prevent Preeclampsia in Next Pregnancy?
At a Glance
Taking low-dose baby aspirin significantly lowers the risk of developing preeclampsia again, though it is not a complete guarantee. Experts recommend starting an 81 mg or 162 mg daily dose between 12 and 16 weeks of pregnancy to promote healthy placental blood vessels.
In this answer
4 sections
If you have had preeclampsia before, you may wonder if taking “baby aspirin” will guarantee it doesn’t happen again. No, taking low-dose aspirin is not a 100% guarantee that you will not develop preeclampsia in your next pregnancy, but it is one of the most effective ways to significantly lower your risk [1][2][3]. For women with a history of preeclampsia, the American College of Obstetricians and Gynecologists (ACOG) strongly recommends taking daily low-dose aspirin to help protect against a recurrence [4][5].
How Low-Dose Aspirin Works
Preeclampsia often begins very early in pregnancy when the placenta is first attaching to the lining of the uterus. Normally, a healthy network of blood vessels forms to supply the baby with oxygen and nutrients. In preeclampsia, these blood vessels don’t develop as well as they should, which restricts blood flow and raises the mother’s blood pressure later in pregnancy.
Low-dose aspirin helps prevent this by promoting healthier blood vessel formation in the placenta [1][6]. It fixes a chemical imbalance in your body between thromboxane (which causes blood vessels to narrow) and prostacyclin (which helps them open and relax) [7]. Aspirin also helps reduce inflammation and prevents small blood clots from forming in the placenta [8][9].
Why It Is a Protection, Not a Cure
While low-dose aspirin is a powerful tool for risk reduction, preeclampsia is a complex condition with multiple causes—or what doctors call biological heterogeneity [1][2]. Because different underlying factors can trigger the disease, aspirin is highly effective for many women but may not block every pathway that leads to preeclampsia [3]. This means that even if you take aspirin perfectly every single day, you still need to be vigilant about warning signs like severe headaches, vision changes, sudden swelling, or pain in your upper right belly.
When to Start (and Stop) Taking It
Timing is critical for aspirin to be effective. ACOG recommends starting a daily low-dose aspirin between 12 and 28 weeks of pregnancy—ideally before 16 weeks [10][11]. Starting before 16 weeks gives the aspirin time to help shape the early development of the placenta’s blood vessels [12][13]. However, if you are past the 16-week mark, starting up until 28 weeks still offers important protective benefits and is strongly recommended [10].
Many maternal-fetal medicine specialists recommend taking your aspirin dose at bedtime, as some research suggests nighttime dosing may offer better blood pressure control.
You will generally continue taking daily aspirin until delivery [11]. It is safe to take up until you give birth, and doing so will not stop you from being able to get an epidural or put you at risk for severe bleeding during labor [11][14].
Dosage and Safety
A standard “baby aspirin” in the United States is 81 milligrams (mg). ACOG guidelines typically recommend a daily dose of 81 mg [4][5]. However, depending on your specific risk factors, some doctors may recommend taking two pills for a total of 162 mg, as some research suggests higher doses can offer additional benefits for high-risk patients [15][16][17].
Extensive research shows that low-dose aspirin is safe for both you and your baby [18][19]. It does not significantly increase the risk of bleeding complications for the mother, nor does it harm the developing baby [11][14]. As with any medication, always talk to your doctor before starting to make sure it is safe for you, especially if you have an aspirin allergy, a history of stomach ulcers, or asthma triggered by NSAIDs (non-steroidal anti-inflammatory drugs like ibuprofen).
Common questions in this guide
Does taking baby aspirin guarantee I won't get preeclampsia again?
When should I start taking aspirin to prevent preeclampsia?
What time of day is best to take baby aspirin during pregnancy?
What is the recommended dose of aspirin to prevent preeclampsia?
Will taking aspirin during pregnancy stop me from getting an epidural?
Questions to Ask Your Doctor
Curated prompts to bring to your next appointment.
- 1.Given my specific history with preeclampsia, do you recommend I take 81 mg or 162 mg of low-dose aspirin?
- 2.When exactly in this pregnancy should I start taking the aspirin, and do you recommend I take it at a specific time of day like bedtime?
- 3.Are there any contraindications based on my health history, such as stomach issues or allergies, that mean I shouldn't take aspirin?
- 4.Will taking aspirin up until delivery affect my pain management options, like getting an epidural, during labor?
- 5.What specific early warning signs of preeclampsia should I be watching for, even while taking the aspirin?
Questions For You
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References
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This page is for informational purposes only and does not replace professional medical advice. Always consult your obstetrician or maternal-fetal medicine specialist before starting or stopping any medication during pregnancy.
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