"[T]he campaign for birth control is not merely of eugenic value, but is practically identical in ideal with the final aims of eugenics ... [T]he most urgent problem today is how to limit and discourage the overfertility of the mentally and physically defective. ... Possibly drastic and Spartan methods may be forced upon society if it continues complacently to encourage the chance and chaotic breeding that has resulted from our stupidly cruel sentimentalism."
Margaret Sanger, “The Eugenic Value of Birth Control Propaganda," Birth Control Review, Oct. 1921, p. 5, emphasis added
In this article, Sanger explains in what way she disagrees with eugenics: she does not believe in encouraging the "fit” to have more children–“positive eugenics”. But she does approve of limiting the fertility of the “unfit”–“negative eugenics.”