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Low-Dose Aspirin Use for the Prevention of Preeclampsia and Related Morbidity and Mortality

  • Practice Advisory PA
  • December 2021

This Practice Advisory was developed by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine in collaboration with Allison S. Bryant, MD, MPH; Alison G. Cahill, MD, MSCI; Jeffrey A. Kuller, MD; Judette M. Louis, MD, MPH; and Mark A. Turrentine, MD.


Background

Low-dose aspirin has been used during pregnancy most commonly to prevent or delay the onset of preeclampsia 1. The previous recommendation from the American College of Obstetricians and Gynecologists (ACOG), the Society for Maternal-Fetal Medicine (SMFM), and the U.S. Preventive Services Task Force (USPSTF) has been for low-dose aspirin (81 mg/d) prophylaxis after 12 weeks of gestation in pregnant individuals at high risk of preeclampsia and suggested low-dose aspirin prophylaxis in pregnant individuals with more than one moderate-risk factor 1,2. ACOG and SMFM also have provided more detailed information around timing, recommending that low-dose aspirin be initiated between 12 weeks and 28 weeks of gestation (optimally before 16 weeks) and continued daily until delivery 1.

USPSTF 2021 Recommendation

In September 2021, the USPSTF published updated recommendations on aspirin use to prevent preeclampsia and related morbidity and mortality 3. The recommendations continue to be based on only risk factors that can be obtained from a patient’s medical history. The primary USPSTF recommendation remains largely unchanged: prescribe low-dose (81 mg/d) aspirin after 12 weeks of gestation to individuals who are at high risk for preeclampsia (Grade B). However, the USPSTF provided updated guidance regarding moderate-risk factors. Specifically, the USPSTF now recommends low-dose aspirin for individuals with more than one moderate-risk factor. Additionally, the USPSTF added one new moderate-risk factor, “In vitro conception,” and modified the previous “Sociodemographic characteristics” risk factor by splitting it into two distinct factors: “Black persons (due to social, rather than biological, factors)” and “lower income.” The USPSTF notes that “Black persons” and “lower income” are associated with increased risk due to environmental, social, and historical inequities shaping health exposures, access to health care, and the unequal distribution of resources, not biological propensities; low-dose aspirin can be considered without any additional moderate-risk factor if the patient has either of these risk factors 3.

Updated ACOG and SMFM Recommendation

Based on the updated USPSTF guidance and its supporting evidence, ACOG and SMFM are revising their recommendation regarding low-dose aspirin prophylaxis for the prevention of preeclampsia. Low-dose aspirin (81 mg/d) prophylaxis is recommended for:

  • Pregnant individuals at high risk of preeclampsia with one or more of the following risk factors:
    • History of preeclampsia, especially when accompanied by an adverse outcome
    • Multifetal gestation
    • Chronic hypertension
    • Pregestational type 1 or 2 diabetes
    • Kidney disease
    • Autoimmune disease (ie, systemic lupus erythematous, antiphospholipid syndrome)
    • Combinations of multiple moderate-risk factors

These risk factors are consistently associated with the greatest risk for preeclampsia. Preeclampsia incidence would likely be at least 8% in a population of pregnant individuals having one of these risk factors.

  • Pregnant individuals with more than one of several moderate risk factors:
    • Nulliparity
    • Obesity (ie, body mass index > 30)
    • Family history of preeclampsia (ie, mother or sister)
    • Black race (as a proxy for underlying racism)
    • Lower income
    • Age 35 years or older
    • Personal history factors (eg, low birth weight or small for gestational age, previous adverse pregnancy outcome, >10-year pregnancy interval)
    • In vitro fertilization

These factors are independently associated with moderate risk for preeclampsia, some more consistently than others. A combination of multiple moderate-risk factors may place a pregnant person at higher risk for preeclampsia.

Additionally, low-dose aspirin can be considered if the patient has one or more of the following moderate-risk factors: Black race (as a proxy for underlying racism), or lower income. The underlying risk to health is racism and not race. However, there are not yet adequate tools for measuring the known impact of racism on health. Therefore, in this document, Black race serves as a proxy for underlying racism. These factors are associated with increased risk due to environmental, social, structural, and historical inequities shaping health exposures, access to health care, and the unequal distribution of resources, not biological propensities.

When recommended, low-dose aspirin should be initiated between 12 weeks and 28 weeks of gestation (optimally before 16 weeks) and continued daily until delivery 1.

Implementation Considerations

Evidence supports the use of a risk-based approach to determine whether low-dose aspirin should be offered to a pregnant individual. It is therefore imperative that obstetrician–gynecologists and other obstetric clinicians implement adequate screening processes to determine the appropriate risk category for a pregnant individual. However, for some institutions and practices, the majority of patients may be at high or moderate risk for preeclampsia and would therefore be candidates for low-dose aspirin prophylaxis. In these instances, universal implementation (eg, offering low-dose aspirin to all patients within such practices or institutions) may be medically reasonable.

This Practice Advisory serves as an interim update to all of ACOG's and SMFM’s guidance and materials regarding low-dose aspirin prophylaxis for the prevention of preeclampsia and related morbidity and mortality.


References

  1. Low-dose aspirin use during pregnancy. ACOG Committee Opinion No. 743. American College of Obstetricians and Gynecologists. Obstet Gynecol 2018;132:e44-52. doi: 10.1097/AOG.0000000000002708
    Article Locations:
    Article LocationArticle LocationArticle LocationArticle Location
  2. LeFevre ML. Low-dose aspirin use for the prevention of morbidity and mortality from preeclampsia: U.S. Preventive Services Task Force recommendation statement. U.S. Preventive Services Task Force. Ann Intern Med 2014;161:819-26. doi: 10.7326/M14-1884
    Article Locations:
    Article Location
  3. Davidson KW, Barry MJ, Mangione CM, Cabana M, Caughey AB, Davis EM, et al. Aspirin use to prevent preeclampsia and related morbidity and mortality: US Preventive Services Task Force Recommendation Statement. US Preventive Services Task Force. JAMA 2021;326:1186-91. doi: 10.1001/jama.2021.14781
    Article Locations:
    Article LocationArticle Location

A Practice Advisory is issued when information on an emergent clinical issue (e.g. clinical study, scientific report, draft regulation) is released that requires an immediate or rapid response, particularly if it is anticipated that it will generate a multitude of inquiries. A Practice Advisory is a brief, focused statement issued within 24-48 hours of the release of this evolving information and constitutes ACOG clinical guidance. A Practice Advisory is issued only on-line for Fellows but also may be used by patients and the media. Practice Advisories are reviewed periodically for reaffirmation, revision, withdrawal or incorporation into other ACOG guidelines.

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