  In order to solve the Tolman-Oppenheimer-Volkoff equations for neutron stars,
one routinely uses the equation of states which are computed in the Minkowski
spacetime. Using a first-principle approach, it is shown that the equation of
states which are computed within the curved spacetime of the neutron stars
include the effect of gravitational time dilation. It arises due to the
radially varying interior metric over the length scale of the star and
consequently it leads to a much higher mass limit. As an example, for a given
set of parameters in a $\sigma-\omega$ model of nuclear matter, the maximum
mass limit is shown to increase from $1.61 M_{\odot}$ to $2.24 M_{\odot}$ due
to the inclusion of gravitational time dilation.
