What defines peripartum onset in mood disorders?

Peripartum onset in mood disorders is specifically characterized by the onset of a mood episode during pregnancy or in the immediate postpartum period. More precisely, the DSM-5-TR identifies peripartum onset as occurring during pregnancy or within four weeks following delivery. This designation captures mood episodes that may arise during this critical and transitional phase, reflecting changes in hormonal levels, physical health, stress, and emotional adjustments that accompany childbirth.

Hence, the correct option emphasizes the time frame of up to four weeks after delivery, allowing healthcare providers to identify and address mood disorders that may significantly affect new parents during this vulnerable period. The emphasis on this four-week window is crucial, as it can help delineate peripartum disorders from those that might arise later and could be indicative of different clinical courses or treatment needs.