Generally, aspirin isn’t recommended during pregnancy unless you have certain medical conditions.
Low-dose aspirin — 60 to 100 milligrams daily — 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.
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.
Source : Myo Clinic