The American College of Pediatricians (ACPeds) maintains that it is unethical to intentionally harm an innocent human being even in the absence of the individual's ability to perceive pain. However, in this paper, ACPeds reviews the laboratory and clinical evidence which indicates that as early as 12 weeks gestation (and possibly earlier) exposure to noxious stimuli negatively affects immature human beings. Because of the resulting acute stress responses and subsequent potential long-term negative effects, the ACPeds holds that avoiding, mitigating, and directly treating fetal, neonatal, and pediatric pain is a medical and ethical obligation.