Heart rate variability (HRV) reflects the autonomic nervous system activity on the organism. Sympathetic and parasympathetic influences in response to painful or stressful stimulus can be measured by the variations of RR intervals. After the elaboration of an automated index evaluating parasympathetic tone in adults (Analgesia Nociception Index, ANI), we choose to adapt this technology to neonates. A work system analysis of the maternity and the neonatal intensive care unit has established the needs for such an application and users' requirements the application should meet. Based on these observations, neonatal applications have been developed for an automated analysis of neonatal HRV in high frequencies only ( ) which is representative of parasympathetic activity. Technical developments have resulted in two specific devices (one ambulatory and one monitor) displaying a unique index: the Newborn Infant Parasympathetic Evaluation (NIPE). Several clinical studies have been carried out and they have shown that the NIPE index is able to evaluate prolonged pain, acute pain, discomfort, and comfortable stimulations. The NIPE index assesses the parasympathetic tone and could be a good decision support for medical staff. Long term studies are needed in order to evaluate the neuro-developmental benefits of continuously parasympathetic evaluation on neonates.