  Standard perturbative quantum gravity formalism is applied to compute the
lowest order corrections to the spatially flat cosmological FLRW solution
governed by ordinary matter. The presented approach is analogous to the one
used to compute quantum corrections to the Coulomb potential in
electrodynamics, or to the approach applied in computation of quantum
corrections to the Schwarzschild solution in gravity. In this framework, it is
shown that the corrections to the classical metric coming from the one-loop
graviton vacuum polarization (self-energy) have (UV cutoff dependent) repulsive
properties, which could be not negligible in the very early Universe.
