  We derive a general expression for the power spectra of scalar and tensor
fluctuations generated during inflation given an arbitrary choice of boundary
condition for the mode function at a short distance. We assume that the
boundary condition is specified at a short-distance cutoff at a scale $M$ which
is independent of time. Using a particular prescription for the boundary
condition at momentum $p = M$, we find that the modulation to the power spectra
of density and gravitational wave fluctuations is of order $(H/M)$, where $H$
is the Hubble parameter during inflation, and we argue that this behavior is
generic, although by no means inevitable. With fixed boundary condition, we
find that the shape of the modulation to the power spectra is determined
entirely by the deviation of the background spacetime from the de Sitter limit.
