This article shows how feminists and counterculture environmentalists employed the term "nature" to create contradictory rationales in support of unmedicated childbirth in the 1970s United States. These arguments began in the 1930s and 1940s, when the women and physicians who first popularized the phrase "natural birth" equated nature with a domestic ideal. In the 1960s and 1970s, feminists and counterculture environmentalists continued to advocate natural birth, but for contradictory reasons. Feminists celebrated women's physical capacities and independence from male physicians but wrestled with the definition of "natural" as they distanced themselves from domesticity and mandatory motherhood. Counterculture environmentalists, meanwhile, celebrated family intimacy and primitivist nostalgia. For them, natural childbirth was part of a larger commitment to environmentalist virtue in a dangerous world. The history of natural birth allows us to see that the social construction of motherhood grew in dialogue, but not in harmony, with the social construction of nature.