Always speak with your provider before starting low dose aspirin or any other medication.
Ever heard the phrase “the dose makes the poison”? Think of it this way: apples contain a teeny tiny amount of the chemical arsenic, which can be dangerous in large doses, but is harmless in the amount encountered in nature’s candy.
The medical community has understood the risks associated with full-strength aspirin (325 mg or higher) use during pregnancy for years, and in fact, the FDA cautions pregnant women against taking full-strength aspirin at all during pregnancy. However, there’s quite a bit of evidence that low-dose aspirin (81 mg) can help prevent preeclampsia from developing in women at risk for preeclampsia, and that these benefits outweigh any risks that aspirin might introduce.
Who should take low-dose aspirin during pregnancy?
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
When should I start low-dose aspirin therapy?
ACOG and the Society for Maternal-Fetal Medicine recommend that candidates for low-dose aspirin begin their daily regimen between 12 and 28 weeks, and ideally before 16 weeks. Therapy should typically be continued daily until delivery.
Does it matter when I take my low-dose aspirin?
Yes! Research shows that aspirin is most effective at bedtime when compared to morning, afternoon, and evening dose times.
How effective is low-dose aspirin?
According to one Cochrane Review, low-dose aspirin therapy might reduce one’s risk of developing preeclampsia by about 18%. More studies are certainly needed, but there’s plenty of evidence that low-dose aspirin is effective.
The bottom line
Preeclampsia is a serious pregnancy complication that can result in negative outcomes for both mother and baby. Taking low-dose aspirin doesn’t guarantee that you won’t develop preeclampsia, but it certainly lowers the risk.
You should speak with your healthcare provider if you have any questions about low-dose aspirin, or your risk of developing preeclampsia.
- “Aspirin Use to Prevent Preeclampsia and Related Morbidity and Mortality: Preventive Medication.” USPSTF. 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, Ayala DE, Fernández JR, Mojón A, Alonso I, Silva I, 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.
- “Frequently Asked Questions About Aspirin.” The Preeclampsia Foundation. Preeclampsia.org. Last Updated on Wednesday, January 17, 2018. Retrieved at: https://www.preeclampsia.org/health-information/53-health-information/672-aspirin
- “Preeclampsia”. March of Dimes. marchofdimes.org. Last reviewed: December, 2017.
- ACOG Committee Opinion Number 743. “Low-Dose Aspirin Use During Pregnancy.” ACOG. American College of Obstetricians and Gynecologists, May 2018. Web. Retrieved at: https://www.acog.org/Clinical-Guidance-and-Publications/Committee-Opinions/Committee-on-Obstetric-Practice/Low-Dose-Aspirin-Use-During-Pregnancy?IsMobileSet=false.