Clinical decisions made in the delivery setting as to whether to employ vaginal delivery or cesarean section are often made under high pressure, and with great uncertainty, and have serious consequences for mother and baby. Now, a new study of electronic health records spanning 86,000 deliveries suggests that if their prior patient had complications in one delivery mode, a physician will be more likely to switch to the other — and likely inappropriate — delivery mode for the subsequent patient, regardless of whether it is warranted for that patient’s indications.