From the FDA Drug Label
If pregnant or breast-feeding ask a health professional before use. it is especially important to use aspirin during the last 3 months of pregnancy unless definitely directed to do so by a doctor because it may cause problems in the unborn child or complications during delivery. The risks of taking aspirin in the third trimester of pregnancy include:
- problems in the unborn child
- complications during delivery Aspirin should only be used during this time if definitely directed to do so by a doctor 1
From the Research
Taking aspirin during the third trimester of pregnancy is generally not recommended due to significant risks, but the most recent and highest quality study suggests that low-dose aspirin can be continued until delivery without complication, as long as it is used under close medical supervision. The primary concern with taking aspirin during the third trimester is that it inhibits platelet function and can increase bleeding risk during delivery for both mother and baby 2. Additionally, aspirin can cause premature closure of the ductus arteriosus in the fetus, a blood vessel that is essential for fetal circulation. This medication may also delay the onset of labor and prolong pregnancy.
For women who need pain relief or fever reduction in the third trimester, acetaminophen (Tylenol) is typically considered safer. If you've been taking low-dose aspirin for prevention of preeclampsia or other conditions, consult your healthcare provider about when to stop before delivery. Women with certain high-risk conditions may sometimes continue low-dose aspirin under close medical supervision, but this is determined on a case-by-case basis by healthcare providers. The most recent study suggests that low-dose aspirin can improve maternal vascular endothelial function without increasing the risks of adverse maternal and perinatal outcomes, and it appears safe to use low-dose aspirin as a prophylactic until delivery 3.
Some key points to consider when taking aspirin during pregnancy include:
- The risk of bleeding and other complications
- The potential benefits of low-dose aspirin in preventing preeclampsia and fetal growth restriction
- The importance of close medical supervision when taking aspirin during pregnancy
- The need to weigh the potential benefits and risks of aspirin use on a case-by-case basis. It's also important to note that individual factors, such as weight and comorbidities, can impact the response to aspirin, and dose modification may be necessary to achieve the optimal response 2.