This sheet is about exposure to low-dose aspirin in pregnancy and while breastfeeding. This information is based on published research studies. It should not take the place of medical care and advice from your healthcare providers.
What is aspirin?
Aspirin, also known as acetylsalicylic acid, is a medication used to reduce inflammation (swelling), fever, and pain. It can also help prevent blood clots and is used to treat or reduce the risk of conditions such as heart attack and stroke. Aspirin belongs to a group of medications called non-steroidal anti-inflammatory drugs (NSAIDs).
NSAIDs, including regular-strength and high-strength aspirin, are not preferred pain relievers during pregnancy. In October 2020, the U.S. Food and Drug Administration (FDA) recommended avoiding the use of NSAIDs, including regular-strength aspirin, after 20 weeks of pregnancy unless your healthcare provider determines it is necessary. This recommendation does not apply to low-dose aspirin used under the guidance of a healthcare provider for specific pregnancy-related reasons. More information about regular-strength aspirin can be found in the MotherToBaby fact sheet: https://mothertobaby.org/fact-sheets/regular-strength-aspirin/.
What is low-dose aspirin?
Low-dose aspirin ranges from 60 to 162 mg daily. The usual dose taken during pregnancy to treat or prevent certain conditions is 81 mg daily.
Sometimes when women find out they are pregnant, they think about changing how they take their medication, or stopping it altogether. However, it is important to talk with your healthcare providers before making any changes to how you take your medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy.
I take low-dose aspirin. Can it make it harder for me to get pregnant?
Low-dose aspirin is not expected to make it harder to get pregnant. A study that included women who had one or two previous pregnancy losses found that taking low-dose aspirin at least 4 days a week increased the chance of pregnancy.
Does taking low-dose aspirin increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. Taking low-dose aspirin as directed by a healthcare provider is not expected to increase the chance of miscarriage. Some studies have shown that taking low-dose aspirin before pregnancy might help lower the chance of miscarriage in some women who have had one or more miscarriages before 20 weeks of pregnancy.
Does taking low-dose aspirin increase the chance of birth defects?
Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at research studies to try to understand if an exposure, like low-dose aspirin, might increase the chance of birth defects in a pregnancy.
Studies on the use of low-dose aspirin during pregnancy have not found a higher chance of birth defects.
Does taking low-dose aspirin in pregnancy increase the chance of other pregnancy-related problems?
Taking low-dose aspirin as directed by a healthcare provider is not expected to increase the chance of pregnancy-related problems, such as preterm delivery (birth before week 37 of pregnancy) or low birth weight (weighing less than 5 pounds, 8 ounces [2,500 grams] at birth).
Studies suggest that low-dose aspirin may improve pregnancy outcomes for some women by increasing blood flow to the uterus and reducing inflammation. It may also lower the chance of preterm delivery and preeclampsia (high blood pressure during pregnancy with possible effects on organs, such as the kidneys). Preeclampsia can lead to seizures, a condition called eclampsia. Pregnant women should take low-dose aspirin only under the guidance of their healthcare provider.
Does taking low-dose aspirin in pregnancy affect future behavior or learning for the child?
Limited information on low-dose aspirin exposure during pregnancy does not suggest an increased chance of developmental problems in infants at 18 months of age. Studies following children up to 5 years of age, including those born before 33 weeks of pregnancy, found no differences in learning or behavior between children exposed to low-dose aspirin during pregnancy and those who were not exposed. Another study found no differences in learning or brain development in children 33 to 39 months old after prenatal exposure to low-dose aspirin.
Breastfeeding while taking low-dose aspirin:
Low-dose aspirin passes into breast milk in small amounts. Occasional use of low-dose aspirin is not expected to increase risks to a breastfeeding infant. Regular-strength aspirin (more than 325 mg) is not preferred during breastfeeding. More information about regular-strength aspirin can be found in the MotherToBaby fact sheet: https://mothertobaby.org/fact-sheets/regular-strength-aspirin/. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a man takes low-dose aspirin, could it affect fertility or increase the chance of birth defects?
It is not known if low-dose aspirin could affect a man’s fertility (ability to make healthy sperm) or increase the chance of birth defects. In general, exposures that fathers or sperm donors have are less likely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.
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