Is it safe to take reclast (zoledronic acid) while pregnant or breastfeeding?

No: Not studied, none of this class of drugs is.

No: Reclast (zoledronic acid) is a powerful suppressor of bone remodeling which is the natural manner in which the bones of fetuses and children grow and shape themselves. Furthermore, Reclast (zoledronic acid) is the only member of its class which appears to bind to protein, so it might even cross the placenta, although this is unknown. There is absolutely no reason, without any exception, to take Reclast (zoledronic acid) during pregnancy or lactation.