An added benefit is that the puppy will come to associate pleasant consequences (getting a treat) with being held by your child. (nevadahumanesociety.org)
We also know that dogs repeat behaviors that have a history of pleasant consequences. (houstonpettalk.com)
According to American psychologist Edward Thorndike and his Law of Effect, «any behaviour that is followed by pleasant consequences is likely to be repeated, and any behaviour followed by unpleasant consequences is likely to be stopped.» (petsmagazine.com.sg)