  We compute the one loop self-mass-squared of a massless, minimally coupled
scalar which is Yukawa-coupled to a massless Dirac fermion in a general
conformally flat background. Dimensional regularization is employed and a fully
renormalized result is obtained. For the special case of a locally de Sitter
background our result is manifestly de Sitter invariant. By solving the
effective field equations we show that the scalar mode functions acquire no
significant one loop corrections. In particular, the phenomenon of
super-adiabatic amplification is not affected. One consequence is that the
scalar-catalyzed production of fermions during inflation should not be reduced
by changes in the scalar sector before it has time to go to completion.
