Generally, aspirin isn't recommended during pregnancy unless you have certain medical conditions.
Use of low-dose aspirin — 60 to 100 milligrams (mg) daily — hasn't been found to be harmful during pregnancy and is sometimes recommended for pregnant women with recurrent pregnancy loss, clotting disorders and preeclampsia.
However, use of higher doses of aspirin poses various risks depending on the stage of pregnancy. During the first trimester, use of higher doses of aspirin poses a concern for pregnancy loss and congenital defects. Taking higher doses of aspirin during the third trimester increases the risk of the premature closure of a vessel in the fetus's heart. Use of high-dose aspirin for long periods in pregnancy also increases the risk of bleeding in the brain of premature infants. If you need to take aspirin during your third trimester of pregnancy, your health care provider will likely closely monitor you and your baby.
The U.S. Food and Drug Administration (FDA) also recommends avoiding use of nonsteroidal anti-inflammatory drugs (NSAIDs) after week 19 of pregnancy, unless your health care provider advises it. Aspirin is a type of NSAID. The concern is that aspirin use could cause rare but serious kidney problems in unborn babies. This could lead to low levels of amniotic fluid surrounding a baby and possible complications.
The typical over-the-counter, low-dose aspirin is 81 mg (previously referred to as baby aspirin). If you are taking low-dose aspirin during pregnancy due to a medical condition, continue doing so as directed by your health care provider. If you need to take a pain reliever during pregnancy, talk to your health care provider about the options. He or she might suggest occasional use of acetaminophen (Tylenol, others) instead of aspirin.