Bisphosphonates cause fetal harm in animals, and animal data suggest that uptake of bisphosphonates into fetal bone is greater than into maternal bone.
Maternal deaths at the time of delivery were observed in female rats given this drug orally at doses greater than or equal to 3 times human exposure. Exposure of pregnant rats during the period of organogenesis resulted in visceral variations (renal pelvis ureter syndrome) and interference with natural delivery (dystocia). Dystocia could be partially reversed by calcium supplementation. In pregnant rats dosed orally maternal toxicity, including dystocia and mortality, fetal perinatal and postnatal mortality, were observed at doses equivalent to human exposure at the recommended daily and greater than or equal to 4 times the recommended once-monthly dose. There are no data on fetal risk and pregnancy in humans.

AU, UK: Use should be avoided.
US: This drug should not be used during pregnancy unless the benefit outweighs the risk to the fetus.

AU TGA pregnancy category: B3
US FDA pregnancy category: C

Comments: There is a theoretical risk of fetal harm (e.g., skeletal and other abnormalities) if pregnancy occurs after completing a course of bisphosphonate therapy.

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AU, UK: Use should be avoided.
US: Caution is recommended.

Excreted into human milk: Unknown
Excreted into animal milk: Yes

Comments: The effects in the nursing infant are unknown.

See references