title: Serum and red-blood-cell folate demonstrate differential associations with BMI in pregnant women.
abstract: To examine the association between BMI and folate concentrations in serum and red blood cells (RBC) in pregnant women.
  
  
  
  A cross-sectional comparison of folate concentrations in serum and RBC sampled simultaneously from the same individual.
  
  
  
  The Ottawa Hospital and Kingston General Hospital, Ontario, Canada.
  
  
  
  Pregnant women recruited between 12 and 20 weeks of gestation.
  
  
  
  A total of 869 pregnant women recruited from April 2008 to April 2009 were included in the final analysis. Serum folate was inversely associated and RBC folate positively associated with BMI, after adjusting for folic acid supplementation, age, gestational age at blood sample collection, race, maternal education, annual income, smoking and MTHFR 677C→T genotype. In stratified analyses, this differential association was significant in women with the MTHFR CC variant. In women with the CT and TT variants, the differential associations were in the same direction but not significant. Folic acid supplementation during pregnancy did not alter the differential association of BMI with serum and RBC folate concentration. This indicates that the current RBC folate cut-off approach for assessing risk of neural tube defects in obese women may be limited.
  
  
  
  BMI is inversely associated with serum folate and positively associated with RBC folate in pregnant women, especially for those with the MTHFR CC variant.
authors.affiliation: 1Department of Epidemiology and Health Statistics,School of Public Health,Central South University,Changsha,Hunan,People's Republic of China.
authors.forename: Minxue
authors.initials: M
authors.lastname: Shen
authors.affiliation: 2OMNI Research Group,Department of Obstetrics and Gynecology, Faculty of Medicine,University of Ottawa,Ottawa,Ontario,Canada.
authors.forename: Shazia Hira
authors.initials: SH
authors.lastname: Chaudhry
authors.affiliation: 5Nutrition Research Division,Health Canada,Ottawa,Ontario,Canada.
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: MacFarlane
authors.affiliation: 2OMNI Research Group,Department of Obstetrics and Gynecology, Faculty of Medicine,University of Ottawa,Ottawa,Ontario,Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: Gaudet
authors.affiliation: 6Department of Obstetrics and Gynecology,Queen's University,Kingston,Ontario,Canada.
authors.forename: Graeme N
authors.initials: GN
authors.lastname: Smith
authors.affiliation: 3Ottawa Hospital Research Institute,Clinical Epidemiology Program,501 Smyth Road,Ottawa,Ontario,Canada,K1H 8L6.
authors.forename: Marc
authors.initials: M
authors.lastname: Rodger
authors.affiliation: 2OMNI Research Group,Department of Obstetrics and Gynecology, Faculty of Medicine,University of Ottawa,Ottawa,Ontario,Canada.
authors.forename: Ruth Rennicks
authors.initials: RR
authors.lastname: White
authors.affiliation: 2OMNI Research Group,Department of Obstetrics and Gynecology, Faculty of Medicine,University of Ottawa,Ottawa,Ontario,Canada.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Walker
authors.affiliation: 1Department of Epidemiology and Health Statistics,School of Public Health,Central South University,Changsha,Hunan,People's Republic of China.
authors.forename: Shi Wu
authors.initials: SW
authors.lastname: Wen
mesh_terms: D000328:Adult; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D004912:Erythrocytes / Q000737:chemistry*; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006801:Humans; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics; D009436:Neural Tube Defects; D009864:Ontario; D011247:Pregnancy
chemical_list: D005492:Folic Acid; C573423:MTHFR protein, human; D042965:Methylenetetrahydrofolate Reductase (NADPH2)
keywords: BMI; Folate; Folic acid; Obesity; Pregnancy