  It is usually assumed that the inflationary fluctuations start from the
Bunch-Davies (BD) vacuum and the $i\varepsilon$ prescription is used when
interactions are calculated. We show that those assumptions can be verified
explicitly by calculating the loop corrections to the inflationary two-point
and three-point correlation functions. Those loop corrections can be resumed to
exponential factors, which suppress non-BD coefficients and behave as the
$i\varepsilon$ factor for the case of the BD initial condition. A new technique
of loop chain diagram resummation is developed for this purpose. For the non-BD
initial conditions which is setup at finite time and has not fully decayed,
explicit correction to the two-point and three-point correlation functions are
calculated. Especially, non-Gaussianity in the folded limit is regularized due
to the interactions.
