This sheet talks about exposure to low dose aspirin in pregnancy and while breastfeeding. This information should not take the place of medical care and advice from your healthcare provider.
What is low dose aspirin?
Aspirin is also known as acetylsalicylic acid. It is a common prescription and over-the-counter medication similar to other non-steroidal inflammatory drugs (NSAIDs) like ibuprofen (Motrin®) and naproxen (Aleve®). Aspirin reduces inflammation, fever, and pain. Aspirin can prevent blood clots, which can make it useful in treating or preventing conditions like heart attacks and strokes.
Low dose aspirin ranges from 60 to 150 mg daily, but the usual dose taken during pregnancy to treat or prevent certain conditions is 81 mg daily.
Regular strength and high strength aspirin and other NSAIDs are NOT preferred pain relievers during pregnancy.
Sometimes when people find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take this 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 people who had 1 or 2 documented pregnancy losses then asked to take daily low dose aspirin found that taking low dose aspirin at least 4 days a week increased the chance of a pregnancy.
Does taking low dose aspirin increase the chance for miscarriage?
Miscarriage can occur in any pregnancy. Taking low doses of aspirin is not thought to increase the chance of miscarriage. Some studies have shown that taking low dose aspirin before pregnancy may help lower the chance of miscarriage in some people who have had one or more miscarriages before 20 weeks of pregnancy. These findings are similar to studies that showed improved pregnancy outcomes in people undergoing assisted reproductive technologies (fertility treatments) and were treated with low dose aspirin prior to implantation of the fertilized egg into the uterus.
Does taking low dose aspirin increase the chance of birth defects?
Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. 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 cause other pregnancy problems. Studies have shown that low dose aspirin might improve pregnancy outcomes in some people by increasing blood flow to and reducing inflammation or swelling in the uterus. Studies have also shown that low dose aspirin might lower the chances for preeclampsia (dangerously high blood pressure and pregnancy complications) in people who are at high risk for this condition. However, people who are pregnant should only take low dose aspirin if their healthcare provider recommends it.
Does taking low dose aspirin in pregnancy affect future behavior or learning for the child?
There are not many studies about long-term effects for children exposed to low dose aspirin during pregnancy. However, studies have not found an increased chance for problems with physical or mental development in infants at 18 months of age. A study that looked at children up to 5 years of age who were born very early (before 33 weeks) and who were exposed to low dose aspirin during pregnancy did not find an effect on their learning or behavior compared to children who were not exposed to low dose aspirin during pregnancy.
Breastfeeding while taking low dose aspirin:
The occasional use of low dose aspirin (75 mg daily to below 300 mg daily) is not expected to increase risks to a breastfeeding infant. Only small amounts of low dose aspirin enter the breast milk and adverse effects have not been reported in breastfed newborns or older infants. Healthcare providers might recommend low dose aspirin in some people during breastfeeding to treat certain medical conditions. However, regular strength aspirin (over 325 mg) is not preferred during breastfeeding.
Aspirin eliminates from an infant’s body more slowly than from an adult’s body, so aspirin levels in the infant’s body could build up over time with long-term use of aspirin. Using high dose aspirin can lower the body’s ability to clot blood (could lead to easier bruising or bleeding). This is not likely to happen with low dose aspirin. Talk with your healthcare provider about your breastfeeding questions.
If a male takes low dose aspirin, could it affect fertility (ability to get partner pregnant) or increase the chance of birth defects?
There is very limited information about the effects of low dose aspirin on male reproduction. One study looked at men who attended an infertility clinic and were taking non-prescribed low dose aspirin at different doses and frequencies for at least six months. The study reported a decrease in the amount and quality of sperm, especially in those who used higher amounts of aspirin. Generally, it is not considered necessary for men to stop using low dose aspirin before trying to get their partner pregnant. However, men undergoing fertility treatment may want to talk with their healthcare providers about whether or not they need to stop taking aspirin.
In general, exposures that fathers or sperm donors have are unlikely to increase the 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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OTIS/MotherToBaby encourages inclusive and person-centered language. While our name still contains a reference to mothers, we are updating our resources with more inclusive terms. Use of the term mother or maternal refers to a person who is pregnant. Use of the term father or paternal refers to a person who contributes sperm.