  We present an analytic expression for the finite temperature effective
sublattice magnetization which would be detected by inelastic neutron
scattering experiments performed on a two-dimensional square-lattice quantum
Heisenberg antiferromagnets with short range N\'eel order. Our expression,
which has no adjustable parameters, is able to reproduce both the qualitative
behaviour of the phase diagram $M(T)xT$ and the experimental values of the
N\'eel temperature $T_{N}$ for either doped YBa$_{2}$Cu$_{3}$O$_{6.15}$ and
stoichiometric La$_{2}$CuO$_{4}$ compounds. Finally, we remark that by
incorporating frustration and 3D effects as perturbations is sufficient to
explain the deviation of the experimental data from our theoretical curves.
