Can Low-dose Aspirin Prevent Women From Pregnancy Loss?
Introduction
Low-dose aspirin, also known as baby aspirin, is a medication that is typically taken at a dose of 81mg per day. It works by preventing the formation of blood clots in the body, which can be beneficial for preventing pregnancy loss. However, it is important to note that low-dose aspirin is not recommended for all women who are trying to conceive or are pregnant and should not be taken without the guidance and supervision of a healthcare provider. This is because there are potential risks associated with taking aspirin during pregnancy, such as bleeding and stomach irritation. Additionally, taking aspirin without knowing the cause of pregnancy loss can lead to serious health conditions for the mother and baby.
The American College of Obstetricians and Gynecologists (ACOG), the Society for Maternal-Fetal Medicine, and the U.S. Preventive Services Task Force (USPSTF) all recommend low-dose aspirin for certain women who are at high risk for pregnancy loss. These include women who have had recurrent pregnancy losses, women with antiphospholipid syndrome or thrombophilia, and women who are pregnant with twins or other multiples.
In this blog, we will delve into the topic of low-dose aspirin and its effects during pregnancy. We will cover how it works, who can benefit from taking it, and who should avoid it. Additionally, we will examine the potential risks associated with using low-dose aspirin during pregnancy. We will also provide recommendations on aspirin use during pregnancy from reputable organizations, such as the American College of Obstetricians and Gynecologists, the Society for Maternal-Fetal Medicine, and the U.S. Preventive Services Task Force, to raise awareness on this topic.
Pregnancy Loss
Pregnancy loss refers to the loss of a fetus before birth and encompasses both miscarriage and stillbirth. Miscarriage occurs before 20 weeks of pregnancy when the fetus is no longer viable and stillbirth happens after 20 weeks of pregnancy when the fetus dies before birth.
The majority of pregnancy losses are caused by chromosomal genetic abnormalities, particularly in the first trimester, such as Trisomy 13, 18, and 21 disorders. A small percentage of pregnancy loss is linked to maternal health issues like autoimmune diseases, hormonal imbalances, and inflammatory disorders, for example, Antiphospholipid Syndrome (APS), Systemic Lupus Erythematosus (SLE), Preeclampsia, untreated hypothyroidism, uncontrolled diabetes mellitus. These pregnancy losses caused by maternal conditions occur at any stage of pregnancy.
Recurrent pregnancy loss is defined as having two or more pregnancy losses (ACOG) and affects around 1-2% of pregnant women. Although many recurrent pregnancy loss cases are mainly associated with genetic factors and maternal health conditions, almost half of all cases remain unexplained.
Low-dose aspirin, how it works, and why it is important for some women
Aspirin, also known as a Non-Steroidal Anti-Inflammatory Drug (NSAID), is a medication that serves as a pain reliever and blood thinner. It works by blocking pain signals in the body, reducing pain, fever, and inflammation. Additionally, when it acts as a blood thinner, it prevents platelets from clumping and clotting in the blood vessels, improving blood flow to vital organs such as the brain, heart, and placenta. This is particularly useful in treating cardiovascular diseases and preeclampsia.
Low-dose aspirin refers to taking a daily dose of 60-100mg (81mg in the U.S.). During pregnancy, a woman's body may be more prone to blood clots. By taking low-dose aspirin as a blood thinner, it can improve placental blood flow and decrease the risk of developing preeclampsia and Antiphospholipid Syndrome (APS) during pregnancy. These autoimmune disorders are closely linked to placental insufficiency, pregnancy loss, thrombosis, fetal growth restriction, and preterm births. Therefore, it is recommended for women with risk factors for preeclampsia and APS to take a low-dose aspirin daily during pregnancy.
Preeclampsia and Its complications and risk factors
Preeclampsia, as described by the American College of Obstetricians and Gynecologists (ACOG) in 2013, is a multi-system inflammatory disorder characterized by high blood pressure (≥140/90 mm Hg) that affects various organs such as the liver, kidneys, brain, blood, and placenta. It typically develops during the second half of pregnancy or after delivery and may or may not be accompanied by protein in the urine.
About 5% of pregnancies in the United States end in Preeclampsia. The majority of cases (90%) present after 34 weeks of pregnancy or postpartum and have good outcomes for both the mother and baby. However, 10% of cases occur before 34 weeks and can result in serious morbidity and mortality for both the mother and baby, such as preterm births, fetal growth restriction, pregnancy loss, and cardiovascular and renal diseases. Additionally, 6-19% of preterm births in the U.S. are caused by Preeclampsia.
The exact cause of Preeclampsia is unknown, but there are several risk factors associated with its development. Moderate risk factors include maternal age ≥35, BMI ≥30, family history of Preeclampsia, first pregnancy, race, and poverty. In the U.S., non-Hispanic black women are at a higher risk of developing Preeclampsia due to racial and social disparities in childbirth, such as lack of access to early prenatal care and early pregnancy referrals, caused by historical and social structural factors. High-risk factors for Preeclampsia include a history of Preeclampsia, multiple pregnancies, autoimmune dysfunction (e.g., APS, SLE), chronic hypertension, uncontrolled diabetes (type 1 & 2), and kidney disease. Women who have at least one high-risk factor or more than one moderate-risk factor are at an increased risk of developing Preeclampsia.
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What is APS, and what are the complications in pregnancy?
Antiphospholipid Syndrome (APS) is an autoimmune disorder characterized by the production of abnormal antibodies that attack phospholipids in cells. This self-attack increases the likelihood of blood clots (thrombosis) and low platelet count (thrombocytopenia). When thrombosis occurs in vital organs such as the placenta, uterus, kidney, liver, and brain, it can lead to serious pregnancy complications, including pregnancy loss, high blood pressure, preeclampsia, fetal growth restriction, and preterm births. Pregnant women with APS are five times more likely to experience miscarriage or stillbirth, particularly during the second and third trimesters.
APS affects 1-5% of the population, with most cases occurring in women, up to 40% of whom have SLE. APS also affects 15% of recurrent pregnancy loss. The exact cause of APS is unknown, but it is thought to be linked to environmental, hormonal, and genetic factors. As it is an autoimmune disorder, there is no cure for APS. However, certain medications such as aspirin and heparin can help reduce the risk of blood clots. For women with APS-related pregnancy loss, taking low-dose aspirin daily can improve placental blood flow and lower the risk of pregnancy loss. Women with APS-related recurrent pregnancy loss have more than a 70% chance of having a successful pregnancy.
Recommendations on using low-dose aspirin in pregnancy
Many studies have shown that taking low-dose aspirin can improve blood flow to the placenta and uterus, lower the risk of Preeclampsia and APS, and reduce the incidence of pregnancy complications such as pregnancy loss, preterm birth, and fetal growth restriction. As a result, the American College of Obstetricians and Gynecologists (ACOG), the Society for Maternal-Fetal Medicine, and the U.S. Preventive Services Task Force (USPSTF) recommend low-dose aspirin for women at high risk for Preeclampsia or APS, and for those with more than one moderate risk factor for Preeclampsia.
The best time to start taking low-dose aspirin is between 12-28 weeks of pregnancy, ideally before 16 weeks, and continuing until giving birth. Studies have also shown that taking low-dose aspirin at bedtime is more effective than taking it in the morning due to its impact on blood pressure control during the night. However, low-dose aspirin is not recommended for preventing early pregnancy loss, unexplained stillbirth, fetal growth restriction, and preterm birth in the absence of high-risk factors for Preeclampsia or APS.
Risks and contraindications of aspirin use in pregnancy
Like any medication, low-dose aspirin also comes with potential side effects. Expectant mothers should be fully informed about the potential side effects of aspirin on both themselves and their babies before deciding to take it to prevent Preeclampsia and APS.
For the mother, aspirin can irritate the stomach lining and cause gastrointestinal ulcers and bleeding, especially in women who are prone to bleeding.
For the baby, recent studies have not found a clear connection between low-dose aspirin use and certain complications such as intracranial hemorrhage, preterm closure of the ductus arteriosus, and congenital anomalies. However, there have not been enough studies on the use of high doses of aspirin during pregnancy, and it is unclear whether some birth defects may be related to the use of high-dose aspirin. It is important to note that every pregnancy carries a small risk of birth defects.
There are certain contraindications to using low-dose aspirin during pregnancy. It is not safe for women with aspirin allergy, hypersensitivity to NSAIDs, nasal polyps, asthma, gastrointestinal ulcers, or conditions that increase the risk of bleeding.
Conclusion
In conclusion, pregnancy loss is a traumatic and unexpected event that can occur during pregnancy. Chromosomal genetic abnormalities are the main cause of early pregnancy loss, while maternal medical conditions account for a small percentage of miscarriages. Genetic and maternal health conditions are responsible for half of the pregnancy loss in the later stages of pregnancy, particularly in recurrent cases, while the remaining cases are unexplained.
Preeclampsia and APS are closely linked to miscarriage and stillbirth, and low-dose aspirin prophylaxis has been shown to reduce blood clots and improve blood flow. However, it should only be recommended for women at high risk for these conditions during pregnancy. Low-dose aspirin will not prevent pregnancy loss caused by chromosomal abnormalities or unexplained causes. It is important for pregnant women to be fully informed about the potential risks of long-term aspirin use during pregnancy.
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