Beck, Cheryl Tatano, a nursing theorist whose Postpartum Depression Theory asserts that postpartum depression results from a feeling of loss of control due to a combination of physiological, psychological, and environmental stressors and that symptoms are varied and likely to be multiple. Beck describes four stages of postpartum depression (encountering terror, dying of self, struggling to survive, and regaining control) and identifies 22 key propositions related to postpartum depression.