This invention relates to novel preformed stabilizers in which a portion of the polymer control agent is recovered and comprises from 10 to 1500 ppm of an inhibitor. This invention also relates to a process for preparing these preformed stabilizers, and to polymer polyols comprising these novel preformed stabilizers macromers and to a process for preparing polymer polyols comprising these novel preformed stabilizers. The present invention also relates to polyurethane foams comprising these polymer polyols, and to processes for preparing these polyurethane foams.