title: Relative validity of a food frequency questionnaire for pregnant women.
abstract: OBJECTIVE
  Pregnant women's diets should be monitored to ensure adequacy, but few studies have assessed the validity of dietary assessment tools among pregnant women. We examined the relative validity of a self-administered, semiquantitative food frequency questionnaire (FFQ) adapted for use in the International Trial of Antioxidants in the Prevention of Preeclampsia for assessing usual diet during pregnancy.
  
  
  METHODS
  A subsample (n=107) was recruited for the FFQ validation study, and provided three days of nonconsecutive three-day food records (3D-FRs) following completion of the FFQ.
  
  
  RESULTS
  Mean ± standard deviation (median) energy intakes (kcal/kJ) from the FFQ and mean of 3D-FRs were 1963 ± 610 (1860)/8219 ± 2554 (7787) and 2320 ± 607 (2354)/9713 ± 2541 (9856), respectively. Spearman correlation coefficients between unadjusted FFQ and 3D-FRs nutrients were positive (rS ranged from 0.17 for iron to 0.49 for folate) and were generally statistically significant (0.05<p<0.01). Most energy-adjusted correlations were less robust. Cross-classification of energy and 24 nutrients from the FFQ and means of the 3D-FRs placed 35% of them into identical quartiles and 75% into identical and contiguous quartiles; only 6% were frankly misclassified. Bland-Altman plots showed acceptable agreement between the two instruments.
  
  
  CONCLUSIONS
  These results suggest that the FFQ is a relatively valid instrument for determining usual diet in pregnant women.
authors.affiliation: Département de nutrition, Université de Montréal, and Centre de recherche, Institut universitaire de gériatrie de Montréal, Montreal, QC, Canada.
authors.forename: Bryna
authors.initials: B
authors.lastname: Shatenstein
authors.forename: Hairong
authors.initials: H
authors.lastname: Xu
authors.forename: Zhong-Cheng
authors.initials: ZC
authors.lastname: Luo
authors.forename: William
authors.initials: W
authors.lastname: Fraser
mesh_terms: D000293:Adolescent; D000328:Adult; D002170:Canada; D004032:Diet; D015930:Diet Records; D005260:Female; D006801:Humans; D008875:Middle Aged; D015596:Nutrition Assessment; D011247:Pregnancy; D011795:Surveys and Questionnaires; D055815:Young Adult