Over the course of the 20th Century, breast milk banks have facilitated the exchange of breast milk from mothers with an excess supply to infants in need. But while early banks used a seller model, purchasing milk as a commodity from lower class women, today banks use a donor model, relying on middle class women who give their milk away as a gift. This dissertation explores why the commodified model of breast milk banking first arose, and why banked breast milk was giftified (but still commodified) by the end of the century. I use content analysis of institutional records from three banks operating in three different eras, and interviews with current milk bank managers, donors, and parents of recipients to address these questions. My analysis indicates that in each era a confluence of factors, in particular women's employment, conceptions of motherhood, medical practices and beliefs, and technologies shapes the exchange of banked breast milk. In the early 20th century new technologies made the physical disembodiment of breast milk possible, while mothering practices and medical authorities' preferences promoted breast milk's symbolic disembodiment, promoting the milk's commodification, while limited employment opportunities created a pool of willing sellers. During the 1960s new mothering practices and related changes in physicians' preferences sacralized the milk, making its sale by mothers culturally inappropriate. Today, high levels of maternal employment and portable, efficient breast pumps create an excess supply of milk that mothers are loath to dispose of due to its sacralized status, sustaining the donor model. But banks still sell the milk as a commodity, albeit a non-profit one, to parents who use the milk both as food and as a form of good parenting in a bottle. Breast milk banking therefore involves both gift and commodity exchange. And as interviews with donors and parents of recipients demonstrate, many middle class donors want to be paid, while middle class parents who purchase the milk reject the idea of donor compensation, pointing to breast milk's ambiguous status even among those intimately involved in its exchange, and the role of social class in mediating actors' perceptions and experiences
