Implementation of clinical practice guidelines may moderate health care costs, improve care, reduce medicolegal liability, and provide a uniformity in care allowing meaningful investigation of treatments and outcomes. However, new guidelines are often uncritically embraced by clinicians, risk management organizations, insurance companies, and the courts as the standard of care. Adoption of incompletely vetted recommendations can lead to patient harm. Recent recommendations made by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine for assessment and management of labor provide an example of well-intended guidelines adopted uncritically. Ideally, but unattainably, each step in a practice guideline would be supported by results of prospective randomized trials. Usually, data from lower on the hierarchy of proof are included, and the personal or institutional preferences of the guideline developers influence the final product. These multiple resources help illuminate critical issues and balance competing perspectives, but can introduce biases that become embedded in our practice. The new labor management guidelines, which were never shown to be superior (or even equivalent) to current standards, have achieved widespread acceptance. Although they provide a formula for reducing the cesarean rate, they do so without concern for their potentially adverse effects on maternal or neonatal outcome. New guidelines should be outcome-based and address how to practice obstetrics to yield the best possible results for mother and baby.