title: Validity and reproducibility of folate and vitamin B(12) intakes estimated from a self-administered diet history questionnaire in Japanese pregnant women.
abstract: BACKGROUND
  No validated dietary questionnaire for assessing folate and vitamin B(12) intakes during pregnancy is available in Japan. We evaluated the validity and reproducibility of intakes of folate and vitamin B(12) estimated from a self-administered diet history questionnaire (DHQ) in Japanese pregnant women.
  
  
  METHODS
  A sample of 167 healthy subjects with singleton pregnancies in the second trimester was recruited at a private obstetric hospital in metropolitan Tokyo from June to October 2008 (n = 76), and at a university hospital in Tokyo from June 2010 to June 2011 (n = 91). The dietary intakes of folate and vitamin B(12) were assessed using the DHQ. The serum concentrations of folate and vitamin B(12) were measured as reference values in the validation study. To assess the reproducibility of the results, 58 pregnant women completed the DHQ twice within 4-5 week interval.
  
  
  RESULTS
  Significantly positive correlations were found between energy-adjusted intakes and serum concentrations of folate and vitamin B(12) (r = 0.286, p < 0.001 and r = 0.222, p = 0.004, respectively). After excluding the participants with nausea (n = 121), the correlation coefficient for vitamin B(12) increased to 0.313 (p = 0.001). When participants were classified into quintiles based on intakes and serum concentrations of folate and vitamin B(12), approximately 60% were classified in the same or adjacent quintile. The intraclass correlation coefficients of the two-time DHQ were 0.725 for folate and 0.512 for vitamin B(12).
  
  
  CONCLUSIONS
  The present study indicated that the DHQ had acceptable validity and reproducibility for assessing folate and vitamin B(12) intakes in Japanese pregnant women.
authors.affiliation: Department of Midwifery and Women's Health, Division of Health Sciences and Nursing, Graduate School of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. mi-shi@umin.ac.jp
authors.forename: Mie
authors.initials: M
authors.lastname: Shiraishi
authors.forename: Megumi
authors.initials: M
authors.lastname: Haruna
authors.forename: Masayo
authors.initials: M
authors.lastname: Matsuzaki
authors.forename: Ryoko
authors.initials: R
authors.lastname: Murayama
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sasaki
authors.forename: Sachiyo
authors.initials: S
authors.lastname: Murashima
mesh_terms: D000328:Adult; D044466:Asian People; D015415:Biomarkers / Q000032:analysis; D004032:Diet; D015930:Diet Records; D004034:Diet Surveys; D002149:Energy Intake; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage* / Q000097:blood; D006801:Humans; D007407:Interviews as Topic; D015596:Nutrition Assessment; D011247:Pregnancy; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D014041:Tokyo; D014805:Vitamin B 12 / Q000008:administration & dosage* / Q000097:blood
chemical_list: D015415:Biomarkers; D005492:Folic Acid; D014805:Vitamin B 12