In addition to the previous posting, you can also argue that the themes of The Yellow Wallpaper can also relate to modern topics such as the lack of understanding of post-partum depression, the internal battles of women and their psychosocial developments, and the reality of how these two can literally drive a human being into complete despair.
So what themes do we see? First, that socially speaking, the main character is indeed trapped by the lack of scientific understanding of her condition. Second, that she is also a victim of the erroneous remedial methods that are being tested on her. Third, that she, as "the weaker sex", cannot take initiative since she is emotionally and socially dependant on what her husband chooses for her. Fourth, that unfortunately, her husband's good efforts are obstructed by the reality her condition is misunderstood and, therefore, mistreated. Ultimately, her final breakdown will demonstrate the extent to which these unfortunate situations have affected her.
There are actually several important themes mentioned, but an additional theme that is often suggested is that “The Yellow Wallpaper” stems from the circumstances of the narrator as a woman—as a human being—desperately in need of self-sufficiency. In this story, it is about how the female narrator is driven into physical weakness and mental breakdown by what passes in her world as love, solicitude, and the best of medical care. Instinctively, she knows what she needs: work (“congenial work, with excitement and change,” paragraph 13), freedom of movement and beautiful surroundings (a well-decorated room opening onto a garden, paragraph 26), and separation from her overmastering husband (the room she wants has no space for his bed, paragraph 27). Instead, her doctor husband, like her doctor brother, prescribes rest and no writing, constant supervision (by her sister-in-law during the day, by her husband at night), and a room away from outside doors and also with barred windows, a gate at the top of the stairs, and ugliness (ugly furniture and torn and ugly yellow wallpaper)—all of which repel her. She is in a nursery because she is being infantilized, in the sense that she is not allowed to make any decisions for herself. The irony is that, because every suggestion she makes to help herself runs contrary to the medical and psychological knowledge imposed by males who live and move in the outside world, she is thrust into the impossible position of being unable to trust her own instincts. She therefore defers to her husband, persuades herself consciously that he is always right, and speaks again and again of her “dear” husband and sister-in-law who both have nothing but love and concern for her.