The general goal of the present study is to examine the developmental changes caused by melatonin in preterm compared to term newborns. This secretion is studied in child and mother's blood, child's urine, the mother's milk for the women who breastfeed (200 infants and their mothers: 4 groups of 50 infants: 24-27 gestational age (GA) +6d ; 28-32 GA +6d ; 33-36 GA +6d ; 37-41 GA +6d). Secondary aims are the following: determine Melatonin creatinin excretion in preterm infants, correlate between serum melatonin secretion and urinary melatonin and 6-sulfatoxymelatonin excretion, determine endogenous melatonin production in the human pineal, correlate genetic variations between different levels of melatonin in premature infants, assess clinical and neurological outcomes at term.