Animal studies with hydrochlorothiazide have failed to reveal evidence of fetal harm. Animal studies with irbesartan have revealed evidence of fetotoxicity. Early resorption and abortion occurred in rabbits at an irbesartan dose which produced maternal mortality. In humans, use of drugs that act on the renin angiotensin system (RAS) during the second and third trimesters increases fetal and neonatal morbidity and death. There are no controlled data in human pregnancy.

AU TGA pregnancy category D: Drugs which have caused, are suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects. Accompanying texts should be consulted for further details.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.

This drug should not be used during pregnancy and some authorities consider it contraindicated.

AU TGA pregnancy category: D
US FDA pregnancy category: Not assigned

Risk Summary: This drug can cause fetal harm when administered during pregnancy.

Comments: Adequate methods of contraception should be encouraged. Treatment with this drug should be discontinued as soon as possible if a pregnancy is detected.

See references

Use is not recommended and 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: Yes (hydrochlorothiazide); Unknown (irbesartan)
Excreted into animal milk: Yes (irbesartan)

See references