title: A prospective study of prepregnancy dietary iron intake and risk for gestational diabetes mellitus.
abstract: OBJECTIVE
  It is important to identify modifiable factors that may lower gestational diabetes mellitus (GDM) risk. Dietary iron is of particular interest given that iron is a strong prooxidant, and high body iron levels can damage pancreatic β-cell function and impair glucose metabolism. The current study is to determine if prepregnancy dietary and supplemental iron intakes are associated with the risk of GDM.
  
  
  METHODS
  A prospective study was conducted among 13,475 women who reported a singleton pregnancy between 1991 and 2001 in the Nurses' Health Study II. A total of 867 incident GDM cases were reported. Pooled logistic regression was used to estimate the relative risk (RR) of GDM by quintiles of iron intake controlling for dietary and nondietary risk factors.
  
  
  RESULTS
  Dietary heme iron intake was positively and significantly associated with GDM risk. After adjusting for age, BMI, and other risk factors, RRs (95% CIs) across increasing quintiles of heme iron were 1.0 (reference), 1.11 (0.87-1.43), 1.31 (1.03-1.68), 1.51 (1.17-1.93), and 1.58 (1.21-2.08), respectively (P for linear trend 0.0001). The multivariate adjusted RR for GDM associated with every 0.5-mg per day of increase in intake was 1.22 (1.10-1.36). No significant associations were observed between total dietary, nonheme, or supplemental iron intake and GDM risk.
  
  
  CONCLUSIONS
  These findings suggest that higher prepregnancy intake of dietary heme iron is associated with an increased GDM risk.
authors.affiliation: Epidemiology Branch, Division of Epidemiology, Statistics and Prevention Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, USA. bowerska2@mail.nih.gov
authors.forename: Katherine
authors.initials: K
authors.lastname: Bowers
authors.forename: Edwina
authors.initials: E
authors.lastname: Yeung
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Williams
authors.forename: Lu
authors.initials: L
authors.lastname: Qi
authors.forename: Deirdre K
authors.initials: DK
authors.lastname: Tobias
authors.forename: Frank B
authors.initials: FB
authors.lastname: Hu
authors.forename: Cuilin
authors.initials: C
authors.lastname: Zhang
mesh_terms: D000328:Adult; D016640:Diabetes, Gestational / Q000209:etiology*; D004032:Diet; D005260:Female; D006418:Heme / Q000008:administration & dosage; D006801:Humans; D019266:Iron, Dietary / Q000008:administration & dosage / Q000009:adverse effects*; D008460:Meat / Q000009:adverse effects; D011247:Pregnancy; D011446:Prospective Studies; D012907:Smoking / Q000009:adverse effects
chemical_list: D019266:Iron, Dietary; D006418:Heme