Animal studies have shown reproductive toxicity manifested by increased pre- and postnatal mortality, reduced fetal weight, and skeletal retardation. Limited human data have revealed evidence of premature birth (gestational period of 28 to 36 weeks) and low birth weight for gestational age.

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.

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

Comments:
-Some formulations of this drug contain ethanol or methanol which should be taken into consideration if it is taken by a pregnant woman.
-Women of childbearing potential should be appraised of the potential risk to the developing fetus.
-This drug may cause immunosuppression in the infant.

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: Yes

Comments:
-Some formulations contain ethanol or methanol which is present in human milk and will be orally absorbed by the nursing infant.
-Breastfed infants should be monitored if this drug is used during lactation, possibly including measurement of serum levels to rule out toxicity.

-Due to potential effects in the nursing infant, such as immunosuppression, neutropenia, growth retardation, and possible carcinogenesis, this drug is considered contraindicated for use in nursing mothers by the American Academy of Pediatrics.
-Concentration of this drug in human milk varies. Most infants studied did not have detectable blood levels, but 2 infants had measurable levels, one with blood levels in the therapeutic range despite relatively low maternal milk levels.
-Many infants have been breastfed during maternal use of this drug, usually with a concurrent corticosteroid and sometimes with concurrent azathioprine. No reports of adverse effects on infant growth, development, or kidney function were reported, although follow-up examinations have not always been performed or reported.

See references