Flashbacks occur often in The Handmaid's Tale and serve multiple functions. Primarily, they operate as a means of world-building and relating context to the reader—both crucial, given that the story begins in media res. These moments of recollection and memory are more than simple plot devices, however: in The Handmaid's Tale, flashbacks serve as an escape for Offred, through one of the only means she still has left to her. These recollections are also a coping mechanism: if Offred fixes the world of the past in her mind as "real," through memory, she is better able to cope with the horrors of the present by categorizing them as "not real."
In Chapter 9, Offred relates how she feels about these flashbacks, describing them in violent language as "attacks":
I have them, these attacks of the past, like faintness, a wave sweeping over my head. Sometimes it can hardly be bourne.
More than providing reprieve, relief, or a convenient means of moving the plot forward, these flashbacks are semi-traumatic events for Offred. To remember is to mourn, and the acts of remembering and thinking, while cathartic, are also constant reminders to Offred of how drastically and tragically her life has changed.