The heart rate variability assessment of the sympathetic-parasympathetic balance is a strong analytical tool in the autonomic nervous system (ANS) physiology, at each end of life.

In neonatology, it represents an important marker for understanding the breath and cardiac dysfunction, incriminated in the pathophysiology of unexplained death syndrome and apnea-bradycardia of prematurity.

If recent clinical studies conducted by our team highlight a close link between the maturation degree of the ANS and gestational or postnatal age, with a substantial autonomic dysfunction in preterm infants, no study to date has focused profile autonomic maturation in the first two years of life, as that period for the infant is a vulnerability "window" especially cardiopulmonary and neurological.

Psychomotor prognosis of newborns is more serious if prematurity is important and if periventricular leukomalacia or cortical anatomical brain lesions are obvious. However, the conventional imaging (Trans fontanel ultrasound, CT, MRI) is not sufficient in the neonatal period to thoroughly evaluate the neurological risk situations. During the neonatal period, the assessment of autonomic control, in practice easily quantifiable from time and frequency-domain analysis of cardiac RR variability, could be a strong marker, at a given time, from a neurological disorder undetectable by imaging, including sympathetic and parasympathetic nerve conduction dysfunction in some brainstem nuclei and cortical areas.

The postnatal profile of the autonomic balance, as a marker of well ANS regulation could become an additional support to correlate transient or permanent autonomic deficit with a psychomotor development disorder at 2 years of age or later. This tool could be a help to target the children with a neurological risk and to schedule early therapeutic interventions and psychological or educational support.