{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T16:00:00Z","timestamp":1791475200668,"version":"4.3.4"},"reference-count":35,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2025,11,4]],"date-time":"2025-11-04T00:00:00Z","timestamp":1762214400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"European Union\u2014NextGenerationEU","award":["15730"],"award-info":[{"award-number":["15730"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Children"],"abstract":"<jats:p>Background\/Objectives: Melatonin, produced by the placenta and pineal gland, regulates circadian timing and has antioxidant and immunomodulatory actions. After birth, neonatal secretion is low and its circadian pattern matures over months; evidence in preterm neonates is mixed. We longitudinally monitored morning blood melatonin from birth to 38 weeks\u2019 postmenstrual age (PMA) in breast milk-fed preterm neonates, assessing differences by time of birth (day vs. night), PMA, and weight-for-gestational-age (WfGA). Methods: A prospective NICU cohort, conducted within the ProMote study. In total, 132 preterm neonates were recruited from 112 mothers. For infants \u226533 weeks\u2019 GA, three samples were obtained: umbilical cord (available in 94; otherwise at the first NICU admission), day of life (DOL) 4\u20137, and DOL 10\u201314; for infants &lt;33 weeks\u2019 GA, an additional sample at 35\u201336 weeks\u2019 PMA. Melatonin was measured by ELISA. Primary analyses used raw melatonin concentrations in linear mixed-effects models; sensitivity analyses checked robustness. Results: A final sample comprised 122 neonates. Concentrations were low to modest with wide between-neonate variation and no monotonic change across PMA. Mixed models showed no consistent differences by time of birth and no stable WfGA effect; occasional PMA-specific contrasts did not recur at adjacent time points. Umbilical cord concentrations were low, and gestational age at birth did not materially influence levels at a given PMA. Sensitivity analyses led to the same inference. Conclusions: In breast milk-fed preterm neonates, morning serum melatonin from 26\u201338 weeks\u2019 PMA shows substantial individual variability without consistent differences by time of birth, PMA, or WfGA.<\/jats:p>","DOI":"10.3390\/children12111490","type":"journal-article","created":{"date-parts":[[2025,11,4]],"date-time":"2025-11-04T11:11:16Z","timestamp":1762254676000},"page":"1490","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Blood Melatonin in Breast Milk-Fed Preterm Infants: Longitudinal Biomonitoring to 38 Weeks\u2019 Postmenstrual Age (ProMote Study)"],"prefix":"10.3390","volume":"12","author":[{"given":"Theano","family":"Kokkinaki","sequence":"first","affiliation":[{"name":"Department of Psychology, University of Crete, 74150 Rethymno, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Manolis","family":"Tzatzarakis","sequence":"additional","affiliation":[{"name":"Laboratory of Toxicology, Medical School, University of Crete, 70013 Heraklion, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1510-2205","authenticated-orcid":false,"given":"Elena","family":"Vakonaki","sequence":"additional","affiliation":[{"name":"Laboratory of Toxicology, Medical School, University of Crete, 70013 Heraklion, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nicole","family":"Anagnostatou","sequence":"additional","affiliation":[{"name":"Department of Neonatology\/Neonatal Intensive Care Unit, University Hospital of Heraklion, School of Medicine, University of Crete, 70013 Heraklion, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5044-983X","authenticated-orcid":false,"given":"Theano","family":"Roumeliotaki","sequence":"additional","affiliation":[{"name":"Department of Social Medicine, School of Medicine, University of Crete, 70013 Heraklion, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5846-388X","authenticated-orcid":false,"given":"Eleftherios","family":"Panteris","sequence":"additional","affiliation":[{"name":"Department of Neonatology\/Neonatal Intensive Care Unit, University Hospital of Heraklion, School of Medicine, University of Crete, 70013 Heraklion, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maria","family":"Markodimitraki","sequence":"additional","affiliation":[{"name":"Department of Preschool Education, University of Crete, 74150 Rethymno, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ioanna","family":"Kakatsaki","sequence":"additional","affiliation":[{"name":"Department of Neonatology\/Neonatal Intensive Care Unit, University Hospital of Heraklion, School of Medicine, University of Crete, 70013 Heraklion, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9917-4486","authenticated-orcid":false,"given":"Haridimos","family":"Kondylakis","sequence":"additional","affiliation":[{"name":"Computational Biomedicine Laboratory, FORTH-ICS & Computer Science Department, University of Crete, 70013 Heraklion, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3824-2462","authenticated-orcid":false,"given":"Aristidis","family":"Tsatsakis","sequence":"additional","affiliation":[{"name":"Center of Toxicology & Science Applications, Medical School, University of Crete, 70013 Heraklion, Greece"},{"name":"Universidad Ecotec, Km. 13.5 Samborondon, Samborondon 092302, Ecuador"},{"name":"Sechenov IM, First State Medical University, 119991 Moscow, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6256-3309","authenticated-orcid":false,"given":"Eleftheria","family":"Hatzidaki","sequence":"additional","affiliation":[{"name":"Department of Neonatology\/Neonatal Intensive Care Unit, University Hospital of Heraklion, School of Medicine, University of Crete, 70013 Heraklion, Greece"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Joseph, T., Schuch, V., Hossack, D., Chakraborty, R., and Johnson, E. 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