Animal studies have failed to reveal evidence of teratogenicity or fetal harm. 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 C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

This drug should be used during pregnancy only if the benefit outweighs the risk to the fetus.

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

See references

UK: Use should be avoided.
AU and US: This drug should not be used unless there are no safer alternatives.

Excreted into human milk: Yes (hydrochlorothiazide); Unknown (triamterene)
Excreted into animal milk: Yes (triamterene)

Comments: Some authorities consider use of this drug acceptable during lactation if required by the mother and assuming a hydrochlorothiazide dose of 50 mg/day or less.

See references