Acetaminophen and codeine have been found to have no mutagenic potential using the Ames Salmonella- Microsomal Activation test, the Basc test on Drosophila germ cells, and the Micronucleus test on mouse bone marrow. There are no adequate and well-controlled studies in pregnant women. Acetaminophen and codeine phosphate should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Withdrawal signs include irritability, excessive crying, tremors, hyperreflexia, fever, vomiting and diarrhea. These signs usually appear during the first few days of life.
Narcotic analgesics cross the placental barrier.
The closer to delivery and the larger the dose used, the greater the possibility of respiratory depression in the newborn. Narcotic analgesics should be avoided during labor if delivery of a premature infant is anticipated. If the mother has received narcotic analgesics during labor, newborn infants should be observed closely for signs of respiratory depression. The effect of codeine, if any, on the later growth, development, and functional maturation of the child is unknown. Acetaminophen and codeine are excreted in breast milk in small amounts, but the significance of their effects on nursing infants is not known.