Which analgesic should be avoided during the third trimester of pregnancy?

• A. Ampicillin
• B. Loratadine
• C. Acetaminophen
• D. Ibuprofen

Answer: (D)

In the third trimester, the safest approach to analgesia is to avoid drugs that affect fetal prostaglandin levels and circulation. Ibuprofen is an NSAID that crosses the placenta and inhibits prostaglandin synthesis. Prostaglandins keep the ductus arteriosus open before birth, so inhibiting them can cause premature closure of this essential fetal vessel, potentially leading to cardiovascular and respiratory complications, and it can also reduce fetal urine production, contributing to lower amniotic fluid. Because of these risks, ibuprofen should be avoided late in pregnancy. If analgesia is needed, acetaminophen is generally considered safer when used at recommended doses. Ampicillin and loratadine are not analgesics, so they aren’t used for pain relief.