title: Vitamin D Status during Pregnancy: A Longitudinal Study in Swedish Women from Early Pregnancy to Seven Months Postpartum.
abstract: Low vitamin D levels during pregnancy may have negative consequences for the health of both the mother and child. Cross-sectional studies in childbearing women suggest that vitamin D levels are low during pregnancy, but few studies have followed the same women during pregnancy and postpartum. The aims of this study were to longitudinally assess vitamin D status during pregnancy and postpartum and identify the factors associated with vitamin D status in pregnant women in northern Sweden. Between September 2006 and March 2009, 184 women were consecutively recruited at five antenatal primary care clinics. Blood was sampled, and dietary intake was estimated using a food frequency questionnaire with 66 food items/food aggregates and questions on the intake of vitamin supplements at gestational weeks 12, 21, and 35, as well as at 12 and 29 weeks after birth. Plasma 25(OH) vitamin D levels were analyzed using liquid chromatography tandem-mass spectrometry. At least one-third of the women had 25(OH) vitamin D levels <50 nmol/L on at least one sampling occasion. Plasma levels increased slightly over the gestation period and peaked in late pregnancy. The levels reverted to the baseline levels after birth. Multivariate analysis showed that gestational and postpartum week, season, dietary intake of vitamin D, and vitamin supplementation were significantly related to plasma levels. There was also an influence of season on the longitudinal concentration patterns. In conclusion, more than one-third of the women studied had low 25(OH) vitamin D levels, and gestational and postpartum week was related to 25(OH) vitamin D levels after adjustment for season and vitamin D intake.
authors.affiliation: Department of Public Health and Clinical Medicine, Family Medicine, Umeå University, Umeå, Sweden.
authors.forename: Anette
authors.initials: A
authors.lastname: Lundqvist
authors.affiliation: Department of Public Health and Clinical Medicine, Family Medicine, Umeå University, Umeå, Sweden.
authors.forename: Herbert
authors.initials: H
authors.lastname: Sandström
authors.affiliation: Department of Public Health and Clinical Medicine, Epidemiology and Global Health, Umeå University, Umeå, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Stenlund
authors.affiliation: Department of Odontology, Cariology, Umeå University, Umeå, Sweden.
authors.forename: Ingegerd
authors.initials: I
authors.lastname: Johansson
authors.affiliation: Department of Medical Biosciences, Clinical Chemistry, Umeå University, Umeå, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Hultdin
mesh_terms: D000328:Adult; D002853:Chromatography, Liquid; D015331:Cohort Studies; D004032:Diet; D015930:Diet Records; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D009752:Nutritional Status; D049590:Postpartum Period; D011247:Pregnancy; D012621:Seasons; D013472:Sunlight; D011795:Surveys and Questionnaires; D013548:Sweden; D053719:Tandem Mass Spectrometry; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood*; D014815:Vitamins / Q000627:therapeutic use
chemical_list: D014815:Vitamins; D014807:Vitamin D; C104450:25-hydroxyvitamin D