We extend a previ\'ous study of quantum critical dynamics in ferromagnets to the isotropic antiferromagnet. The model we consider here also includes so-called "mode-mode coupling" terms. The quantum limit is found to have the characteristic dimensionality ${d}_{Q}=6$ versus the classical value ${d}_{C}=4$. A renormalization-group expansion to order $\ensuremath{\epsilon}=6\ensuremath{-}d$ is used to evaluate spin and staggered spin transport quantities ${\ensuremath{\Gamma}}_{M}$ and ${\ensuremath{\Gamma}}_{N}$ in the limit of low critical temperature ${T}_{N}$. Dynamic scaling is found to break down in the quantum case and scaling regions of quantum, classical, and "mixed" statistics are discussed in light of this breakdown.