Development of melatonin production in infants and the impact of prematurity.

The development of rhythmic 6-sulfatoxymelatonin excretion in urine was studied in healthy full-term and premature infants during the first 12 months of life. There was little evidence of rhythmic 6-sulfatoxymelatonin excretion before 9 to 12 weeks of age in full-term infants. Over this period, excretion increased five to six times compared to the excretion at 6 weeks (08 +/- 103 vs. 2973 +/- 438 pmol/24 h) with the major proportion of the hormone metabolite being excreted between 0200-1000 h. At 24 weeks of age, total 6-sulfatoxymelatonin excretion was 25% of adult levels. Premature infants (51 +/- 4 days premature) had a delay in the appearance of rhythmic 6-sulfatoxymelatonin of approximately 9 weeks. Even after correcting for gestational age or length of time at home, the premature infants were found to have a 2-3 week delay in the development of 6-sulfatoxymelatonin rhythmicity compared to full-term infants. These results provide evidence that neural centers responsible for rhythm generation and/or t...