Animal studies have failed to reveal evidence of fetal harms. Sulfonamides may cause kernicterus in patients during the first month of life by displacing bilirubin from plasma albumin. There are no controlled data in human pregnancy.

AU TGA pregnancy category C: Drugs which, owing to their pharmacological effects, have caused or may be suspected of causing, harmful effects on the human fetus or neonate without causing malformations. These effects may be reversible. Accompanying texts should be consulted for further details.

US FDA pregnancy category B: Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women.

Use is not recommended unless clearly needed, especially in pregnant women approaching or at term.
-According to some authorities: Use should be avoided during the last month of pregnancy.

AU TGA pregnancy category: C
US FDA pregnancy category: B

See references

A decision should be made to discontinue breastfeeding or discontinue the drug, taking into account the importance of the drug to the mother.

Excreted into human milk: Unknown
Excreted into animal milk: Data not available

Comments: The effects in the nursing infant are unknown.

Sulfonamides are known to be excreted in human milk and all sulfonamide derivatives are known to increase the possibility of kernicterus. There is a possibility for serious adverse reactions in nursing infants from sulfonamides.

See references