Almost all women were oppressed by society during the World War I period. For example, they couldn't vote and often belonged to churches that taught female subordination. However, Catherine is a woman who, as far as possible, doesn't allow herself to be oppressed.

It's often mentioned that Catherine is a static character. She doesn't grow during the course of the novel: her maturation has already been completed by the time she falls in love with Frederic Henry. However, that does not make her weak or subordinate: she is a strong, self-possessed woman who knows what she wants. She is not afraid to enjoy the good things of life: food, drink, sex. She is not afraid to reject institutionalized religion in favor of a personal creed of love: she will not have a priest in her room as she is dying. She rejects the social convention of getting married before she has her baby. She supports herself through her nursing career.

Religion and shaming are social institutions or conventions that have traditionally oppressed women, but Catherine rejects all of that. She won't go to church to conform to social norms, and she couldn't care less if she is judged for being pregnant and unmarried. She knows she and Frederic share a love that doesn't need to be approved by the rest of society. Catherine is a good example of a woman who lives her own life as far as she can and fights off oppression by knowing and sticking to her beliefs.