Always speak with your provider before starting low dose aspirin or any other medication.
You might have heard that aspirin is considered unsafe to take during pregnancy, and in one regard that’s true: full-strength aspirin (325 mg or higher) does increase the risk for certain issues with fetal development. However, more and more data suggest that low-dose aspirin (81 mg) is not only safe to take during pregnancy, but can even reduce the chances of developing preeclampsia if you’re at risk for it.
What is preeclampsia?
Preeclampsia is a pregnancy complication that, according to the March of Dimes, affects 2 to 8 percent of all pregnancies. Preeclampsia involves high blood pressure and signs that organs aren’t working as well as they should be (such as protein in urine). Preeclampsia is usually diagnosed in the third trimester, and if it is, most healthcare providers recommend close observation until delivery. This may mean frequent monitoring in an outpatient setting, or, depending on the severity and the healthcare provider, may mean staying in the hospital until delivery. Preeclampsia’s symptoms usually go away in the days and weeks after giving birth.
Is there any way to prevent preeclampsia?
Because researchers still don’t understand exactly why some women develop preeclampsia, there’s no great one-size-fits-all method of preventing it. However, recent studies suggest that low-dose aspirin therapy can help prevent preeclampsia in women with certain risk factors that make preeclampsia more likely to develop. Women with these risk factors who begin low-dose aspirin therapy around 12 weeks, and continue until delivery, may be about 18% less likely to develop preeclampsia. Talk to your provider to determine if low-dose aspirin is right for you.
Who should take low-dose aspirin to prevent preeclampsia?
The American Congress of Obstetricians and Gynecologists (ACOG) have identified a number of risk factors for developing preeclampsia that make one a good candidate for low-dose aspirin.
ACOG recommends low-dose aspirin therapy for those who have one or more of the following “high” risk factors:
- History of preeclampsia, especially when accompanied by an adverse outcome
- Multifetal gestation
- Chronic hypertension
- Type 1 or 2 diabetes
- Renal disease
- Autoimmune disease (systemic lupus erythematosus, antiphospholipid syndrome)
…or more than one of the following “moderate” risk factors. The US Preventive Service Task Force (USPSTF) states that low-dose aspirin can be considered for those with only one of the following moderate risk factors:
- Family history of preeclampsia (mother or sister)
- Age 35 years or older
- Nulliparity (first-time mom)
- Obesity (BMI > 30)
- Personal history factors (e.g., low birthweight or small for gestational age, previous adverse outcome, more than 10-year pregnancy interval)
- In vitro conception
- Sociodemographic characteristics (African American race, low socioeconomic status)
- Low income
- Racism which leads to environmental, social, and historical inequities that shape health exposures, access to healthcare, and unequal distribution of resources
If have have these risk factors, speak with your provider about if taking a low-dose aspirin could be a good fit for you.
When and how do I take low-dose aspirin?
According to the Preeclampsia Foundation, if you meet the above criteria and your provider recommends it, it’s best to begin a low-dose aspirin regimen between 12 and 16 weeks of pregnancy, and continue right up until delivery. Certain studies also show that taking low-dose aspirin at bedtime might be the most effective time of day to take it. Aspirin should not be taken on an empty stomach.
Does it matter what time I take my dose?
Yes! Research shows that aspirin is most effective at bedtime when compared to morning, afternoon, and evening dose times.
Can I take a generic version of low-dose aspirin?
Sure can! Aspirin is aspirin, no matter the brand.
Does low-dose aspirin have any medical interactions?
Aspirin is known to interact with other medications, such as Tylenol (acetaminophen), fish oil, and different antacids. You should speak with your healthcare provider if you regularly take one of these, and your provider recommends a low-dose aspirin regimen.
Are there any risks associated with low-dose aspirin?
Many authorities have investigated the potential risks of low-dose aspirin therapy, and, fortunately, it’s becoming clear that not only do the pros of low-dose aspirin therapy outweigh any theoretical risks (for those who meet the risk factor criteria), but also that the risks are pretty minimal. In fact, the United States Preventive Services Task Force found:
- No increase in infant loss, growth problems, or cognition harm to the baby;
- No statistically significant impact on risk of placental abruptions, postpartum hemorrhage (bleeding), or miscarriage to the mother;
- No differences in developmental outcomes of the infants up to age 18 months.
There are certainly risks with regular-dose aspirin, so it’s important to make sure that if your prescriber puts you on an aspirin regimen, you’re taking a low dose (81 mg).
If you have a planned C-section, it’s a good idea to discuss your low-dose aspirin regimen with your healthcare provider to determine whether to stop taking it prior to the C-section.
- “Aspirin Use to Prevent Preeclampsia and Related Morbidity and Mortality: Preventive Medication.” USPSTF. September 28, 2021. https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/low-dose-aspirin-use-for-the-prevention-of-morbidity-and-mortality-from-preeclampsia-preventive-medication#tab1.
- Hermida RC, et al. Administration time-dependent effects of aspirin in women at differing risk for preeclampsia. Hypertension. (1999) 34:1016–23. doi: 10.1161/01.hyp.34.4.1016
- “Ask About Aspirin.” The Preeclampsia Foundation. https://www.preeclampsia.org/aspirin Last updated 3 August 2023. Spanish version https://www.preeclampsia.org/aspirina
- ACOG Committee Opinion Number 743. “Low-Dose Aspirin Use During Pregnancy.” ACOG. American College of Obstetricians and Gynecologists, May 2018. Web. Reaffirmed 2023: https://www.acog.org/Clinical-Guidance-and-Publications/Committee-Opinions/Committee-on-Obstetric-Practice/Low-Dose-Aspirin-Use-During-Pregnancy?IsMobileSet=false.