The philosophy of "evidence-based medicine"--basing medical decisions on evidence from randomized controlled trials and other forms of aggregate data rather than on clinical experience or expert opinion--has swept U.S. medical practice in recent years. Obstetricians justify recent increases in the use of cesarean section, and dramatic decreases in vaginal birth following previous cesarean, as evidence-based obstetrical practice. Analysis of pivotal "evidence" supporting cesarean demonstrates that the data are a product of its social milieu: The mother's body disappears from analytical view; images of fetal safety are marketing tools; technology magically wards off the unpredictability and danger of birth. These changes in practice have profound implications for maternal and child health. A feminist project within obstetrics is both feasible and urgently needed as one locus of resistance.