At its core, The Bell Jar, Sylvia Plath's sole novel, explores the societal pressure on young women in the 1950s to marry. Esther's depression is partly driven by her anxiety that she won't be a suitable wife for various reasons: she lacks cooking skills, is too tall, and is not a good dancer. Unfortunately, she sees her strengths—intelligence, ambition, and literary talent—as drawbacks in the marriage market. At times, Esther feels she could never find happiness in any marriage, regardless of her partner.

The Bell Jar is rich with symbolism, with one of the most prominent being the themes of birth and rebirth. In one scene, Esther witnesses a birth at the teaching hospital where Buddy Willard works: "I was so struck by the sight of the table where they were lifting the woman I didn't say a word. It looked like some awful torture table, with these metal stirrups sticking up at midair at one end and all sorts of instruments and wires and tubes...." Her vivid description of the birthing process is accurate but lacks any sense of joy or awe. As Lynda K. Bundtzen notes in Plath's Incarnations, "The problem ... is that men have usurped the privilege of giving birth from women. The doctors are all male and they are entirely responsible for the emergence of a new creature into the world." For Esther, childbirth is not a joyful event; it represents male domination.

The concept of rebirth is symbolically addressed in the novel's ending. Observe Esther's portrayal of the elements: "The sun, emerged from its gray shrouds of clouds, shone with a summer brilliance on the untouched slopes ... I felt the profound thrill it gives me to see trees and grassland waist-high under flood water, as if the usual order of the world had shifted slightly, and entered a new phase."

Some critics suggest that Joan Gilling's death, the character most similar to Esther Greenwood, liberates Esther from some of her suffering. As Stan Smith remarks in Critical Quarterly, "Esther is left wondering, at Joan's funeral, just what she thinks she is burying, the 'wry black image' of her madness, or the 'beaming double of her old best self.' In a sense, the suicide of this surrogate is Esther's rebirth."