title: Development and validation of a vitamin D status prediction model in Danish pregnant women: a study of the Danish National Birth Cohort.
abstract: Vitamin D has been hypothesized to reduce risk of pregnancy complications such as preeclampsia, gestational diabetes mellitus, and preterm delivery. However, many of these outcomes are rare and require a large sample size to study, representing a challenge for cohorts with a limited number of preserved samples. The aims of this study were to (1) identify predictors of serum 25-hydroxy-vitamin D (25(OH)D) among pregnant women in a subsample (N = 1494) of the Danish National Birth Cohort (DNBC) and (2) develop and validate a score predicting 25(OH)D-status in order to explore associations between vitamin D and maternal and offspring health outcomes in the DNBC. In our study sample, 42.3% of the population had deficient levels of vitamin D (<50 nmol/L 25(OH)D) and average levels of 25(OH)D-status were 56.7(s.d. 24.6) nmol/L. A prediction model consisting of intake of vitamin D from diet and supplements, outdoor physical activity, tanning bed use, smoking, and month of blood draw explained 40.1% of the variance in 25(OH)D and mean measured 25(OH)D-level increased linearly by decile of predicted 25(OH)D-score. In total 32.2% of the women were placed in the same quintile by both measured and predicted 25(OH)D-values and 69.9% were placed in the same or adjacent quintile by both methods. Cohen's weighted kappa coefficient (Κ = 0.3) reflected fair agreement between measured 25(OH)D-levels and predicted 25(OH)D-score. These results are comparable to other settings in which vitamin D scores have shown similar associations with disease outcomes as measured 25(OH)D-levels. Our findings suggest that predicted 25(OH)D-scores may be a useful alternative to measured 25(OH)D for examining associations between vitamin D and disease outcomes in the DNBC cohort, but cannot substitute for measured 25(OH)D-levels for estimates of prevalence.
authors: Centre for Fetal Programming, Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark.
authors: Camilla
authors: C
authors: Bjørn Jensen
authors: Andrew L
authors: AL
authors: Thorne-Lyman
authors: Linda
authors: L
authors: Vadgård Hansen
authors: Marin
authors: M
authors: Strøm
authors: Nina
authors: N
authors: Odgaard Nielsen
authors: Arieh
authors: A
authors: Cohen
authors: Sjurdur Frodi
authors: SF
authors: Olsen
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D007229:Infant Welfare / Q000706:statistics & numerical data; D007231:Infant, Newborn; D016014:Linear Models; D039382:Maternal Nutritional Physiological Phenomena; D008429:Maternal Welfare / Q000706:statistics & numerical data; D015999:Multivariate Analysis; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology
chemical_list: D014807:Vitamin D