title: Prenatal exposure to vitamin D from fortified margarine and risk of fractures in late childhood: period and cohort results from 222 000 subjects in the D-tect observational study.
abstract: Prenatal low vitamin D may have consequences for bone health. By means of a nationwide mandatory vitamin D fortification programme, we examined the risk of fractures among 10-18-year-old children from proximate birth cohorts born around the date of the termination of the programme. For all subjects born in Denmark during 1983-1988, civil registration numbers were linked to the Danish National Patient Registry for incident and recurrent fractures occurring at ages 10-18 years. Multiplicative Poisson models were used to examine the association between birth cohort and fracture rates. The variation in fracture rates across birth cohorts was analysed by fitting an age-cohort model to the data. We addressed the potential modification of the effect of vitamin D availability by season of birth. The risk of fractures was increased among both girls and boys who were born before the vitamin D fortification terminated in 1985 (rate ratio (RR) exposed v. non-exposed girls: 1·15 (95 % CI 1·11, 1·20); RR exposed v. non-exposed boys: 1·11 (95 % CI 1·07, 1·14). However, these associations no longer persisted after including the period effects. There was no interaction between season of birth and vitamin D availability in relation to fracture risk. The study did not provide evidence that prenatal exposure to extra vitamin D from a mandatory fortification programme of 1·25 µg vitamin D/100 g margarine was sufficient to influence the risk of fractures in late childhood, regardless of season of birth. Replication studies are needed.
authors.affiliation: 1Department of Clinical Research,Odense Patient Data Explorative Network (OPEN),Odense University Hospital,University of Southern Denmark,5000 Odense C,Denmark.
authors.forename: Mina Nicole
authors.initials: MN
authors.lastname: Händel
authors.affiliation: 2Research Unit for Dietary Studies,Bispebjerg and Frederiksberg Hospital,The Parker Institute and the Institute of Preventive Medicine,2000 Frederiksberg,Denmark.
authors.forename: Peder
authors.initials: P
authors.lastname: Frederiksen
authors.affiliation: 3Medical Research Council Lifecourse Epidemiology Unit,University of Southampton,Southampton SO16 6YD,UK.
authors.forename: Clive
authors.initials: C
authors.lastname: Osmond
authors.affiliation: 3Medical Research Council Lifecourse Epidemiology Unit,University of Southampton,Southampton SO16 6YD,UK.
authors.forename: Cyrus
authors.initials: C
authors.lastname: Cooper
authors.affiliation: 1Department of Clinical Research,Odense Patient Data Explorative Network (OPEN),Odense University Hospital,University of Southern Denmark,5000 Odense C,Denmark.
authors.forename: Bo
authors.initials: B
authors.lastname: Abrahamsen
authors.affiliation: 2Research Unit for Dietary Studies,Bispebjerg and Frederiksberg Hospital,The Parker Institute and the Institute of Preventive Medicine,2000 Frederiksberg,Denmark.
authors.forename: Berit L
authors.initials: BL
authors.lastname: Heitmann
mesh_terms: D000293:Adolescent; D002648:Child; D015331:Cohort Studies; D003718:Denmark; D005260:Female; D005527:Food, Fortified; D050723:Fractures, Bone / Q000517:prevention & control; D006801:Humans; D008297:Male; D008383:Margarine; D011247:Pregnancy; D011248:Pregnancy Complications / Q000178:diet therapy; D011297:Prenatal Exposure Delayed Effects; D039401:Prenatal Nutritional Physiological Phenomena; D012306:Risk; D012621:Seasons; D014807:Vitamin D / Q000627:therapeutic use*; D014808:Vitamin D Deficiency / Q000150:complications / Q000178:diet therapy*; D014815:Vitamins / Q000627:therapeutic use*
chemical_list: D014815:Vitamins; D014807:Vitamin D; D008383:Margarine
keywords:  25(OH)D 25-hydroxy vitamin D ICD International Classification of Diseases; Children; Epidemiology; Fortification; Fracture risk; Vitamin D