title: Season, dietary factors, and physical activity modify 25-hydroxyvitamin D concentration during pregnancy.
abstract: OBJECTIVE
  The objectives of this cross-sectional study were to define maternal and umbilical cord blood (UCB) 25-hydroxyvitamin D (25(OH)D) to characterize maternal factors modifying 25(OH)D during pregnancy and predict UCB 25(OH)D in two subgroups with Declined [Δ25(OH)D <0 nmol/l] and Increased [Δ25(OH)D >0 nmol/l] 25(OH)D concentration.
  
  
  METHODS
  A complete dataset was available from 584 women. 25(OH)D was determined at gestational weeks 6-13 and in UCB. Baseline characteristics were collected retrospectively using questionnaires. Δ25(OH)D was calculated as UCB 25(OH)D-early pregnancy 25(OH)D. Dietary patterns were generated with principal component analysis. Multivariate regression models were applied.
  
  
  RESULTS
  Vitamin D deficiency was scarce, since only 1% had 25(OH)D concentration <50 nmol/l both in early pregnancy and in UCB. Shared positive predictors of UCB 25(OH)D in the subgroups of Declined and Increased, were early pregnancy 25(OH)D (P < 0.001) and supplemental vitamin D intake (P < 0.04). For the Increased subgroup summer season at delivery (P = 0.001) and "sandwich and dairy" dietary pattern characterized with frequent consumption of vitamin D fortified margarine and milk products (P = 0.009) were positive predictors of UCB 25(OH)D. Physical activity (P = 0.041) and maternal education (P = 0.004) were additional positive predictors in the Declined group CONCLUSIONS: Maternal and newborn vitamin D status was sufficient, thus public health policies in Finland have been successful. The key modifiable maternal determinants for 25(OH)D during pregnancy, and of the newborn, were supplemental vitamin D intake, frequent consumption of vitamin D fortified foods, and physical activity.
authors.affiliation: Children's Hospital, University of Helsinki and Helsinki University Hospital, Tukholmankatu 8 C, Biomedicum Helsinki, P.O. Box 20, 00014, Helsinki, Finland.
authors.forename: Helena H
authors.initials: HH
authors.lastname: Hauta-Alus
authors.affiliation: Children's Hospital, University of Helsinki and Helsinki University Hospital, Tukholmankatu 8 C, Biomedicum Helsinki, P.O. Box 20, 00014, Helsinki, Finland.
authors.forename: Elisa M
authors.initials: EM
authors.lastname: Holmlund-Suila
authors.affiliation: Faculty of Agriculture and Forestry, University of Helsinki, Latokartanonkaari 7, P.O. Box 27, 00014, Helsinki, Finland.
authors.forename: Hannu J
authors.initials: HJ
authors.lastname: Rita
authors.affiliation: Children's Hospital, University of Helsinki and Helsinki University Hospital, Tukholmankatu 8 C, Biomedicum Helsinki, P.O. Box 20, 00014, Helsinki, Finland.
authors.forename: Maria
authors.initials: M
authors.lastname: Enlund-Cerullo
authors.affiliation: Children's Hospital, University of Helsinki and Helsinki University Hospital, Tukholmankatu 8 C, Biomedicum Helsinki, P.O. Box 20, 00014, Helsinki, Finland.
authors.forename: Jenni
authors.initials: J
authors.lastname: Rosendahl
authors.affiliation: Children's Hospital, University of Helsinki and Helsinki University Hospital, Tukholmankatu 8 C, Biomedicum Helsinki, P.O. Box 20, 00014, Helsinki, Finland.
authors.forename: Saara M
authors.initials: SM
authors.lastname: Valkama
authors.affiliation: Children's Hospital, University of Helsinki and Helsinki University Hospital, Tukholmankatu 8 C, Biomedicum Helsinki, P.O. Box 20, 00014, Helsinki, Finland.
authors.forename: Otto M
authors.initials: OM
authors.lastname: Helve
authors.affiliation: Children's Hospital, University of Helsinki and Helsinki University Hospital, Tukholmankatu 8 C, Biomedicum Helsinki, P.O. Box 20, 00014, Helsinki, Finland.
authors.forename: Timo K
authors.initials: TK
authors.lastname: Hytinantti
authors.affiliation: National Institute for Health and Welfare, Aapistie 1, P.O. Box 310, 90101, Oulu, Finland.
authors.forename: Heljä-Marja
authors.initials: HM
authors.lastname: Surcel
authors.affiliation: Children's Hospital, University of Helsinki and Helsinki University Hospital, Tukholmankatu 8 C, Biomedicum Helsinki, P.O. Box 20, 00014, Helsinki, Finland.|Center for Molecular Medicine, Karolinska Institutet and Clinical Genetics, Karolinska University Hospital Solna, 171 76, Stockholm, Sweden.|Folkhälsan Research Center, Helsinki, University of Helsinki, Haartmaninkatu 8, P.O. Box 63, 000014, Helsinki, Finland.
authors.forename: Outi M
authors.initials: OM
authors.lastname: Mäkitie
authors.affiliation: Children's Hospital, University of Helsinki and Helsinki University Hospital, Tukholmankatu 8 C, Biomedicum Helsinki, P.O. Box 20, 00014, Helsinki, Finland.
authors.forename: Sture
authors.initials: S
authors.lastname: Andersson
authors.affiliation: Children's Hospital, University of Helsinki and Helsinki University Hospital, Tukholmankatu 8 C, Biomedicum Helsinki, P.O. Box 20, 00014, Helsinki, Finland. heli.viljakainen@helsinki.fi.|Folkhälsan Research Center, Helsinki, University of Helsinki, Haartmaninkatu 8, P.O. Box 63, 000014, Helsinki, Finland. heli.viljakainen@helsinki.fi.
authors.forename: Heli T
authors.identifier: http://orcid.org/0000-0002-7486-3437
authors.initials: HT
authors.lastname: Viljakainen
mesh_terms: D003430:Cross-Sectional Studies; D004032:Diet; D019587:Dietary Supplements; D015444:Exercise / Q000502:physiology*; D005260:Female; D005387:Finland; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy / Q000097:blood*; D012189:Retrospective Studies; D012621:Seasons; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: 25-hydroxyvitamin D concentration; Dietary pattern; Maternal vitamin D status; Newborn vitamin D status; Pregnancy