title: Vitamin D status is inversely associated with anemia and serum erythropoietin during pregnancy.
abstract: BACKGROUND
  Vitamin D and iron deficiencies frequently co-exist. It is now appreciated that mechanistic interactions between iron and vitamin D metabolism may underlie these associations.
  
  
  OBJECTIVE
  We examined interrelations between iron and vitamin D status and their regulatory hormones in pregnant adolescents, who are a group at risk of both suboptimal vitamin D and suboptimal iron status.
  
  
  METHODS
  The trial was a prospective longitudinal study of 158 pregnant adolescents (aged ≤18 y). Maternal circulating biomarkers of vitamin D and iron were determined at midgestation (∼25 wk) and delivery (∼40 wk). Linear regression was used to assess associations between vitamin D and iron status indicators. Bivariate and multivariate logistic regressions were used to generate the OR of anemia as a function of vitamin D status. A mediation analysis was performed to examine direct and indirect relations between vitamin D status, hemoglobin, and erythropoietin in maternal serum.
  
  
  RESULTS
  Maternal 25-hydroxyvitamin D [25(OH)D] was positively associated with maternal hemoglobin at both midgestation and at delivery (P < 0.01 for both). After adjustment for age at enrollment and race, the odds of anemia at delivery was 8 times greater in adolescents with delivery 25(OH)D concentrations <50 nmol/L than in those with 25(OH)D concentrations ≥50 nmol/L (P <0.001). Maternal 25(OH)D was inversely associated with erythropoietin at both midgestation (P <0.05) and delivery (P <0.001). The significant relation observed between 25(OH)D and hemoglobin could be explained by a direct relation between 25(OH)D and hemoglobin and an indirect relation that was mediated by erythropoietin.
  
  
  CONCLUSIONS
  In this group of pregnant adolescents, suboptimal vitamin D status was associated with increased risk of iron insufficiency and vice versa. These findings emphasize the need for screening for multiple nutrient deficiencies during pregnancy and greater attention to overlapping metabolic pathways when selecting prenatal supplementation regimens.
authors.affiliation: Division of Nutritional Sciences.
authors.forename: Carrie E
authors.initials: CE
authors.lastname: Thomas
authors.affiliation: University of Rochester School of Medicine and Dentistry, Rochester, NY.
authors.forename: Ronnie
authors.initials: R
authors.lastname: Guillet
authors.affiliation: University of Rochester School of Medicine and Dentistry, Rochester, NY.
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Queenan
authors.affiliation: University of Rochester School of Medicine and Dentistry, Rochester, NY.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Cooper
authors.affiliation: Division of Nutritional Sciences.
authors.forename: Tera R
authors.initials: TR
authors.lastname: Kent
authors.affiliation: University of Rochester School of Medicine and Dentistry, Rochester, NY.
authors.forename: Eva K
authors.initials: EK
authors.lastname: Pressman
authors.affiliation: Cornell University Statistical Consulting Unit, and.
authors.forename: Francoise M
authors.initials: FM
authors.lastname: Vermeylen
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY; and.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Roberson
authors.affiliation: Division of Nutritional Sciences, koo4@cornell.edu.
authors.forename: Kimberly O
authors.identifier: http://orcid.org/0000-0002-0954-1706
authors.initials: KO
authors.lastname: O'Brien
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood; D000293:Adolescent; D018798:Anemia, Iron-Deficiency / Q000150:complications / Q000453:epidemiology*; D015415:Biomarkers / Q000097:blood; D002112:Calcifediol / Q000097:blood; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004921:Erythropoietin / Q000097:blood*; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D039382:Maternal Nutritional Physiological Phenomena; D009518:New York / Q000453:epidemiology; D009752:Nutritional Status; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000453:epidemiology*; D011446:Prospective Studies; D012306:Risk; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000453:epidemiology*
chemical_list: D015415:Biomarkers; C554270:EPO protein, human; D006454:Hemoglobins; D004921:Erythropoietin; D015652:25-Hydroxyvitamin D 2; D002112:Calcifediol
keywords: anemia; hepcidin; iron; pregnancy; vitamin D