title: Determinants of maternal vitamin D concentrations in Slovenia : A prospective observational study.
abstract: OBJECTIVE
  To analyze the vitamin D status of pregnant women in Slovenia and the factors influencing it.
  
  
  METHODS
  The study was performed in Maribor University Medical Centre (location 46°N). Maternal serum 25-hydroxy-vitamin D (25(OH)D) in 4 groups of 100 pregnant women in 4 different seasons of the year was measured at the time of delivery. Data on life style, eating habits, sunbathing and intake of vitamin D supplements during pregnancy were obtained using a questionnaire. Information on maternal outcome was acquired from medical records. Duration of sunlight and average temperature in the month preceding delivery were calculated from meteorological data.
  
  
  RESULTS
  The average maternal 25(OH)D concentration ranged from 28.5 ± 17.1 nmol/l in March to 54.8 ± 24.1 nmol/l in June (p < 0.001). Severe vitamin D deficiency, i.e. <25 nmol/l 25(OH)D was present in 23.6% of women overall. In multiple regression analysis supplements containing vitamin D (β = 0.225, p < 0.001) and duration of intentional exposure to sunlight (β = 0.192, p = 0.026) were associated with maternal 25(OH)D status. Significantly lower vitamin D levels were observed in women who had a cesarean section (t = 2.053, p = 0.041) and those with premature delivery (t = 2.296, p = 0.022). Vitamin D levels were not associated with the occurrence of gestational diabetes, gestational hypertension or infections during pregnancy.
  
  
  CONCLUSIONS
  A high prevalence of vitamin D deficiency was detected at the end of pregnancy, especially in the months following autumn and winter and in women who did not take supplements containing vitamin D.
authors.affiliation: University Clinic for Gynecology and Perinatology, University Medical Center Maribor, Ljubljanska 5, 2000, Maribor, Slovenia. andrazdovnik@gmail.com.
authors.forename: Andraž
authors.initials: A
authors.lastname: Dovnik
authors.affiliation: University Clinic for Gynecology and Perinatology, University Medical Center Maribor, Ljubljanska 5, 2000, Maribor, Slovenia.
authors.forename: Faris
authors.initials: F
authors.lastname: Mujezinović
authors.affiliation: University Clinic for Gynecology and Perinatology, University Medical Center Maribor, Ljubljanska 5, 2000, Maribor, Slovenia.
authors.forename: Milena
authors.initials: M
authors.lastname: Treiber
authors.affiliation: Department of Internal Medicine, University of Maribor Faculty of Medicine, Taborska 8, 2000, Maribor, Slovenia.
authors.forename: Breda
authors.initials: B
authors.lastname: Pečovnik Balon
authors.affiliation: Department of Laboratory Diagnostics, University Medical Center Maribor, Ljubljanska 5, 2000, Maribor, Slovenia.
authors.forename: Maksimiljan
authors.initials: M
authors.lastname: Gorenjak
authors.affiliation: Department of Pharmacology and Experimental Toxicology, University of Maribor Faculty of Medicine, Taborska 8, 2000, Maribor, Slovenia.
authors.forename: Uroš
authors.initials: U
authors.lastname: Maver
authors.affiliation: University Clinic for Gynecology and Perinatology, University Medical Center Maribor, Ljubljanska 5, 2000, Maribor, Slovenia.|Department of Gynecology and Perinatology, University of Maribor Faculty of Medicine, Taborska 8, 2000, Maribor, Slovenia.
authors.forename: Iztok
authors.initials: I
authors.lastname: Takač
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood* / Q000453:epidemiology*; D011256:Pregnancy Outcome / Q000453:epidemiology; D011446:Prospective Studies; D015203:Reproducibility of Results; D012307:Risk Factors; D012621:Seasons; D012680:Sensitivity and Specificity; D017524:Slovenia / Q000453:epidemiology; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood* / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D014807:Vitamin D
keywords: Nutritional supplements; Pregnancy outcomes; Season; Sunlight; Vitamin D