Constructing Centimeters: Emanuel Friedman's Cervimeter and the Dilatation-Time Curve.

In 1954 Emanuel Friedman created a new dimension for measuring labor-change in dilatation rate over time-allowing the birthing body to participate in defining what it meant for labor to be "arrested." Yet in constructing a "normal" standard curve of dilatation-over-time for guiding labor decisions and constructing a measuring instrument (the "cervimeter") to evidence the shape of this curve, Friedman unintentionally enabled a new dimension of labor to emerge: centimeters of dilation, today read as the state of labor progress. This article examines an oral interview with Friedman, the raw data from his first study, and his published research to show how the cervimeter reified centimeters as an "objectively" measurable interval-scale unit (rather than representing an ordinal approximation felt by hand) and enabled the transformation of Fried-man's curve from a graphical tool meant to conform to women into a tool used to conform them.