-Animal studies have shown no teratogenic or other adverse effects on fetal development at 100 times the recommended weekly human dose based on body surface area; however, there were abortifacient effects after 3 to 5 doses. There were no abortifacient effects at 2 times the recommended human dose.
-Seven women became pregnant during clinical studies; 5 women delivered normal babies at full term and 2 women had spontaneous abortions. Among 32 pregnant patients who were followed in a pregnancy registry, 29 women had live births with no abnormalities at birth, 2 had spontaneous abortions, and 1 had a stillbirth.

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 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.

AU, UK: Use is contraindicated.
US: This drug should be used during pregnancy only if the benefit outweighs the risk.

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

Comments:
-Women of child-bearing potential should take appropriate contraceptive measures.
-If the patient becomes pregnant or plans to become pregnant while taking this drug she should be informed of the potential hazards and discontinuation of therapy should be considered.
-In patients with a high relapse rate before treatment started, the risk of a severe relapse following discontinuation of this drug in the event of pregnancy should be weighed against a possible increased risk of spontaneous abortion.

See references

AU, UK: A decision should be made to discontinue breastfeeding or discontinue the drug, taking into account the importance of the drug to the mother.
US: Caution is advised.

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

Comment:
-The effects in the nursing infant are unknown.

-The levels of this drug in breastmilk are minuscule. Because this drug is poorly absorbed orally, it is not likely to reach the bloodstream of the infant. A small number of nursing mothers receiving this drug while partially breastfeeding their infants and one woman who exclusively breastfed her infant reported no adverse effects.

See references