In the balance: weighing babies and the birth of the infant welfare clinic.

The nineteenth century saw the incorporation of technology, such as the stethoscope, microscope, and thermometer, into clinical medicine. An instrument that has received less attention in the history of the role of technology in medicine is the weighing balance, or scale. Although not new to nineteenth-century medicine, it played an important part in the rise of the numerical method and its application to the development and shaping of pediatrics. This article explores the origin and development of the weighing of babies. During its clinical and scientific adoption, this simple procedure was refined and applied in a number of increasingly sophisticated and far-reaching ways: as a measure of the dimensions of the fetus and newborn, as an index of the viability of the newborn, as a means of estimating milk intake, as a way of distinguishing normality from abnormality, as a summary measure of infant health, and as an instrument of mass surveillance. In so doing it changed the way in which medical care was delivered to infants.