The Yellow Wallpaper is an allegory to the inner pressures and entrapment of women when assigned by society to fulfill a specific role.
The main character is a woman obviously stricken with a tremendous case of PTSD or Post Partum Depression that is completely underrated by her husband as the doctor. Society also ignores the situation of women in general afflicted by illness as a mere case of ill nerves.
However, the affliction she suffers is so intense that her brain begins to play tricks on her, making her believe that there are figures wanting to come out of the Yellow Wallpaper because they are (like her) trapped inside.
Meanwhile, as neither the doctor nor the husband care to find a proper cure or treatment, her condition goes unanswered, and society (as a whole) continues to vindicate women and their needs to an empty, maddening, role of ignorance.
Conclusively, the feminist issues revealed in the story include: The needs of women being underrated, the health of women being considered a secondary need, the psychological afflictions of women not being taken in to consideration, and the inner battles of women and their natures against the pre-established roles that society has established for them.
I would say that the emergence of post partum depression as a valid condition that women endure is one of the most pressing feminist issues revealed in the short story. The manner in which the husband and his sister treat the narrator as someone "who needs rest" and "seclusion" represents one way in which how women's own medical and psychological conditions are misunderstood by a patriarchal social order. There are specific experiences that women endure which require a heightened amount of sensitivity and validation, as opposed to patronizing deferral. At the same time, the underbelly of this repression, her own madness that emerges becomes another feminist element in the short story. Namely, that dismissing women's claims can result in a reality that will be destructive to all, as represented in the ripping of the wallpaper and the condition of the husband upon seeing his wife doing so.
To add to the above response, in some ways this work can be viewed as a captivity narrative - the narrator is trapped in her room (or at least she sees herself as trapped) in much the same way that women have traditionally been held captive by their status as property and their subjugation at the hands of a male-dominated, often misogynistic society.
In this case, the narrator has been imprisoned by her own husband, ostensibly for her own good as she suffers from a nervous condition. However, she is being held captive. One of the essential elements in early feminist literature is the conflict that is presented when a woman seeks to become free of male confinement and from male definition. The fact that her husband is a doctor adds to the degree of subjugation for he is in a position of power historically denied to women and given with an almost "god-like" status that allows him to control her. In this case, she begins to see other women escaping from the patterns on the wallpaper. There are two levels of feminist thought here. The first relates to the escape that these women are achieving - an escape that the narrator, as well, wants to achieve.
On another level, the symbolism of the patterns on the wall becoming the women is also important. Women were kept from the literary realm by restricting their access to education, to publication, and to codification in the rhetorical canon. A form of literary feminist criticism that emerged during the 1970's in France, Écriture féminine, can also be applied to this text. Coined by Cixous and literally meaning "women's writing" the term was adopted in American literary criticism by Elaine Showalter and has been applied to the importance of language and the need to "write the body" or repossess language. Linguistics is rooted in symbols. In this way, the symbols in the wallpaper evolve into the women who are set free - taking back the language and the self simultaneously.