  We consider the application of heavy fermion formalism based chiral
perturbation theory to meson production in nucleon-nucleon collisions. It is
shown that for one loop contributions the heavy fermion formalism expansion
corrections for the nucleon propagator produce infinite series of correction
terms which are of the same momentum power order. This destroys the one-to-one
correspondence between the perturbative and small momentum expansion and thus
negates the application of any finite order heavy fermion formalism chiral
perturbation theory to the $NN\to NN \pi$ reactions.
