After World War I, Sanger increasingly posited a societal need to limit births by those least able to afford children. The affluent and educated already limited their child-bearing, while the poor and uneducated lacked access to contraception and information about birth control. Here she found an area of overlap with eugenicists. She believed that they both sought to "assist the race toward the elimination of the unfit." She distinguished herself from other eugenicists, by writing " imply or insist that a woman's first duty is to the state; we contend that her duty to herself is her duty to the state. We maintain that a woman possessing an adequate knowledge of her reproductive functions is the best judge of the time and conditions under which her child should be brought into the world. We further maintain that it is her right, regardless of all other considerations, to determine whether she shall bear children or not, and how many children she shall bear if she chooses to become a mother." Sanger was a proponent of negative eugenics, which aimed to improve human hereditary traits through social intervention by reducing the reproduction of those who were considered unfit.
