title: Vitamin D metabolite concentrations in umbilical cord blood serum and associations with clinical characteristics in a large prospective mother-infant cohort in Ireland.
abstract: Vitamin D deficiency is widespread among mothers and neonates and quality clinical and analytical data are lacking. We used a CDC-accredited LC-MS/MS method to analyze vitamin D metabolites in cord sera from 1050 maternal-infant dyads in the prospective SCOPE Ireland Pregnancy and BASELINE Birth cohort studies, based in Cork, Ireland. The mean±SD total 25(OH)D was 34.9±18.1nmol/L; 35% of cords (50% during winter) had 25(OH)D <25nmol/L, 46% were <30nmol/L and 80% were <50nmol/L. In this predominantly white cohort, the main predictor of cord 25(OH)D [adj. mean difference in nmol/L (95% CI)] was summer delivery [19.2 (17.4, 20.9), P<0.0001]. Maternal smoking during pregnancy (9% prevalence) was negatively associated (P<0.002) with cord 25(OH)D [-4.83 (-7.9, -1.5) nmol/L]. There were no associations between cord 25(OH)D and birth weight or any anthropometric measures at birth. Despite the high prevalence of vitamin D deficiency at birth, there were no documented musculoskeletal complications during infancy, which was likely due to widespread supplementation with vitamin D. The mean±SD concentration of 3-epi-25(OH)D3, detectable in 99.4% of cord samples, was 3.3±1.9nmol/L. The proportion of 25(OH)D as 3-epi-25(OH)D3was 11.2%. Cord 3-epi-25(OH)D3concentrations were positively predicted by cord 25(OH)D3[0.101 (0.099, 0.103) nmol/L, P<0.0001] and negatively by gestational age [-0.104 (-0.131, -0.076) nmol/L, P<0.0001] and maternal age [-0.010 (-0.019, -0.001) nmol/L, P<0.05]. 25(OH)D2was detected in 98% of cord sera (mean±SD; 2.2±1.9nmol/L) despite low antenatal consumption of vitamin D2supplements. In conclusion, these first CDC-accredited data of vitamin D metabolites in umbilical cord blood emphasise the high risk of very low vitamin D status in infants born to un-supplemented mothers. Experimental data to define maternal vitamin D requirements for prevention of neonatal deficiency at high latitude are required.
authors.affiliation: Cork Centre for Vitamin D and Nutrition Research, School of Food and Nutritional Sciences, University College Cork, Ireland; Irish Centre for Fetal and Neonatal Translational Research [INFANT], University College Cork, Ireland. Electronic address: m.kiely@ucc.ie.
authors.forename: Mairead
authors.initials: M
authors.lastname: Kiely
authors.affiliation: Cork Centre for Vitamin D and Nutrition Research, School of Food and Nutritional Sciences, University College Cork, Ireland; Irish Centre for Fetal and Neonatal Translational Research [INFANT], University College Cork, Ireland.
authors.forename: Sinead M
authors.initials: SM
authors.lastname: O'Donovan
authors.affiliation: Irish Centre for Fetal and Neonatal Translational Research [INFANT], University College Cork, Ireland; Department of Obstetrics and Gynecology, University College Cork, Ireland.
authors.forename: Louise C
authors.initials: LC
authors.lastname: Kenny
authors.affiliation: Irish Centre for Fetal and Neonatal Translational Research [INFANT], University College Cork, Ireland; Department of Pediatrics and Child Health, University College Cork, Ireland.
authors.forename: Jonathan O'B
authors.initials: JO
authors.lastname: Hourihane
authors.affiliation: Department of Clinical Medicine, Trinity College, Dublin, Ireland; Department of Pediatric Dermatology, Our Lady's Children's Hospital, Dublin, Ireland; National Children's Research Centre, Dublin, Ireland.
authors.forename: Alan D
authors.initials: AD
authors.lastname: Irvine
authors.affiliation: Irish Centre for Fetal and Neonatal Translational Research [INFANT], University College Cork, Ireland; Department of Pediatrics and Child Health, University College Cork, Ireland.
authors.forename: Deirdre M
authors.initials: DM
authors.lastname: Murray
mesh_terms: D000328:Adult; D000886:Anthropometry; D002853:Chromatography, Liquid; D015331:Cohort Studies; D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007494:Ireland; D008137:Longitudinal Studies; D008297:Male; D008423:Maternal Age; D011247:Pregnancy; D011446:Prospective Studies; D012621:Seasons; D044967:Serum / Q000737:chemistry*; D012907:Smoking / Q000009:adverse effects; D053719:Tandem Mass Spectrometry; D014470:Umbilical Cord / Q000737:chemistry*; D014807:Vitamin D / Q000097:blood* / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000097:blood
chemical_list: D014807:Vitamin D
keywords: 25-Hydroxyvitamin D; 3-epi-25-hydroxyvitamin D; Vitamin D; Vitamin D deficiency; birth cohort; umbilical cord blood