Obstetricians learned this lesson the hard way. A century ago, very little in obstetric practice was codified. Care was artisanal, variable, and sometimes dangerous. Based on a theory that childbirth is inherently "pathogenic," prominent American obstetricians recommended sweeping reforms. (DeLee, JB, Principles and Practice of Obstetrics, 1913, first edition). This article is protected by copyright. All rights reserved.