Episode 167: Aspirin in Pregnancy
Dr. Marquez explains the use of aspirin during pregnancy to prevent preeclampsia. Dr. Arreaza adds comments and questions and clarifies that aspirin is not used for the treatment of preeclampsia.
Written by Verna Marquez, MD, and Hector Arreaza, MD.
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Introduction to the topic: Pregnancy is a special time in a woman’s life, and we want to make sure that both the mother and the baby are safe and healthy.
1. What is aspirin? Aspirin is one of the most ancient medications in history, it is known as acetyl-salicylic acid (ASA) and it belongs to the family of non-steroidal anti-inflammatory drugs (NSAID), and it is also an anti-platelet, among other properties that may be unknown.
It is widely used for pain, fever, and inflammation, but due to adverse effects during viral illness (i.e. Reye Syndrome), it is used less frequently during viral infections.
As we know, aspirin is widely used to treat myocardial infarction and ischemic stroke, and especially for secondary prevention. The use of aspirin for primary prevention of cardiovascular disease has become less popular, but we are going to leave that discussion for another episode because today we will talk about the use of aspirin in pregnancy!
2. Why should we use aspirin in pregnancy?
Low-dose aspirin in pregnancy is most commonly used to prevent or delay the onset of preeclampsia. Aspirin lowers the risk of preeclampsia by 10% and its consequences (such as growth restriction and preterm birth). Several organizations have agreed on the risk factors we will mention briefly. These organizations are ACOG (American College of Obstetricians and Gynecologists), USPSTF (US Preventive Services Task Force), and SMFM (Society for Maternal-Fetal Medicine).
3. Who should we start on aspirin in pregnancy?
Aspirin is not for every pregnant patient, for example, a healthy nulliparous or any patient who had an uneventful, full-term delivery previously, is considered low risk and should NOT be started on aspirin because there is no benefit in preventing any condition.
Low-dose aspirin is recommended for women who have at least a high-risk factor because the incidence of preeclampsia is about 8% in these patients. The risk factors are:
•Previous pregnancy with preeclampsia (especially early onset and with an adverse outcome)
•Type 1 or 2 diabetes mellitus.
•Chronic hypertension.
•Multifetal gestation.
•Kidney disease.
•Autoimmune disease with potential vascular complications (antiphospholipid syndrome, systemic lupus erythematosus).
Your patient only needs 1 high-risk factor to be put on aspirin in pregnancy.
4. What are the moderate risk factors?
A patient needs to have more than 1 moderate risk factor to meet the criteria for prenatal aspirin.
•Nulliparity.
•Obesity (BMI >30).
•Family history of preeclampsia in mother or sister.
•Age ≥35 years.
•Sociodemographic characteristics (Black persons, lower income level [recognizing that these are not biological factors]).
•Personal risk factors (for example, previous pregnancy with low birth weight or small for gestational age newborn, previous adverse pregnancy outcome [such as stillbirth], interval >10 years between pregnancies). However, low-dose ASA prophylaxis is not recommended solely for the indication of prior unexplained stillbirth in the absence of risk factor for preeclampsia.
•In vitro conception.
USPSTF/ACOG may also suggest aspirin in selected patients with only one moderate risk factor, but it would require consultation with a specialist in obstetrics.
5. When should we start aspirin?
After 12 weeks of gestation, ideally before 16-20 weeks of gestation. If a patient is more than 16 weeks pregnant, aspirin can be started but most of the benefit has been noted when initiated before 16 weeks because many of the abnormalities that cause preeclampsia are developed early in pregnancy. It is not recommended to start before 11 weeks.
It is important to mention also that low-dose aspirin appears to have little or no benefit in patients who already have developed preeclampsia. Starting aspirin in preeclampsia can even cause damage such as bleeding in cases of thrombocytopenia.
6. What is the dose?
The dose is between 75 to 162 mg daily. Conveniently, we have an 81 mg presentation in the United States, and it falls within the recommended range. It can be taken in the morning or at night, and adherence of >90% is associated with better prevention.
7. When do we stop aspirin?
Expert opinion recommends stopping aspirin at the time of delivery.
8. What are the contraindications to ASA use during pregnancy?
Absolute contraindications to aspirin:
-Patients with a history of ASA allergy (urticaria) or hypersensitivity to other salicylates are at risk of anaphylaxis and should not receive low-dose ASA.
-Because of significant cross-sensitivity between ASA and other NSAIDs, low-dose ASA is also contraindicated with known HPS to NSAIDs.
-Exposure to low-dose ASA in patients with nasal polyps may result in life-threatening bronchoconstriction and should be avoided.
Relative contraindications are history of GI bleed, active peptic ulcer disease, other sources of GI or GU bleeding, and severe hepatic dysfunction.
Aspirin is an excellent way to prevent preeclampsia in patients who are at high or moderate risk. Remember to think about the high-risk factors, and if your patient has only 1 positive, then aspirin needs to be started. Mainly, previous preeclampsia, diabetes, hypertension, multifetal gestation, and kidney or autoimmune disease. Look for moderate risk factors and start aspirin if the patient has 2 or more of those risk factors.
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Conclusion: Now we conclude episode number 167, “Aspirin in Pregnancy.” Dr. Marquez explained that aspirin is started between 12-16 weeks of gestation to prevent preeclampsia in patients with at least 1 high-risk factor or patients with 2 or more moderate-risk factors. Dr. Arreaza also mentioned that aspirin is not for low-risk patients or for patients who already developed preeclampsia. As you know, preeclampsia can result in severe consequences for the fetus and the mother, but by preventing it, we can improve the chances of having a positive outcome in pregnancy.
This week we thank Hector Arreaza and Verna Marquez. Audio editing by Adrianne Silva.
Even without trying, every night you go to bed a little wiser. Thanks for listening to Rio Bravo qWeek Podcast. We want to hear from you, send us an email at RioBravoqWeek@clinicasierravista.org, or visit our website riobravofmrp.org/qweek. See you next week!
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References:
- August, Phyllis and Arun Jeyabalan, Preeclampsia: Prevention. UpToDate, Last updated Feb 16, 2024. https://www.uptodate.com/contents/preeclampsia-prevention.
- Aspirin Use to Prevent Preeclampsia and Related Morbidity and Mortality: Preventive Medication, September 28, 2021, United States Preventive Services Taskforce https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/low-dose-aspirin-use-for-the-prevention-of-morbidity-and-mortality-from-preeclampsia-preventive-medication.
- Royalty-free music used for this episode: Tropicality by Gushito, downloaded on July 29, 2023, from https://www.videvo.net/royalty-free-music/.
