Evidence is a spectrum. The US Food and Drug Administration (FDA) Guidance for Industry1 states that “[w]ith regard to quantity, it has been FDA’s position that Congress generally intended to require at least two adequate and well-controlled studies, each convincing on its own, to establish effectiveness.” However, in practice, care is often changed if standard of care is limited, if the underlying disease is severe, or if the new treatment is comparatively safe. In October 2012, a commentary in JAMA stated that “[u]nlike treatments used in other fields of medicine, most medications administered to preterm infants lack convincing data to support their safety and efficacy with more than 90% not approved…for the prescribed indication. No new medications have substantially improved outcome for preterm infants since the introduction of antenatal corticosteroids and surfactant 15 to 20 years ago.”2(p1493) There are many potential reasons for this, including a lack of financial incentives, the expense of clinical trials, the difficulty in conducting trials in neonatal intensive care units, and FDA regulations. This need not be the case, as more than 5 well-conducted clinical trials have shown that probiotics can greatly improve the mortality and morbidity of preterm infants. We call for a paradigm shift in US neonatal intensive care units with an impact potential similar to that seen with the universal uptake of respiratory surfactant.