title: An estimation of periconceptional under-reporting of dietary energy intake.
abstract: BACKGROUND
  The purpose of this cross-sectional study was to examine periconceptional misreporting of energy intake (EI) using the Willet food frequency questionnaire (WFFQ).
  
  
  METHODS
  Women were recruited in the first trimester. Women completed a semi-quantitative WFFQ. Maternal body composition was measured using eight-electrode bioelectrical impedance analysis. Under-reporters were those whose ratio of EI to their calculated basal metabolic rate fell below the calculated plausible threshold for their physical activity category.
  
  
  RESULTS
  The mean age was 30.1 ± 5.3 years (n = 524). The mean body mass index (BMI) was 25.4 ± 5.6 kg/m(2), and 16.6% were obese (BMI ≥ 30.0 kg/m(2)). Under-reported EI was observed in 122 women (23.3%) with no over-reporters in the sample. Under-reporters were younger (P < 0.001), less likely to have a normal BMI (P = 0.002) and more likely to be obese (P < 0.001) than plausible reporters. Under-reporters had higher percentage of body-fat and lower percentage of body fat-free mass (P < 0.001), were more likely to be at risk of relative deprivation (P = 0.001) and reported a higher percentage of EI from carbohydrate (P = 0.02) than plausible reporters.
  
  
  CONCLUSIONS
  Observed differences between under-reporters and plausible reporters suggest that the exclusion of these under-reporters represents an important potential source of bias in obesity research among women in the periconceptional period.
authors.affiliation: School of Biological Sciences, Dublin Institute of Technology, Dublin 8, Republic of Ireland.
authors.forename: Laura
authors.initials: L
authors.lastname: Mullaney
authors.affiliation: UCD Centre for Human Reproduction, Coombe Women and Infants University Hospital, Dublin 8, Republic of Ireland.
authors.forename: Amy C
authors.initials: AC
authors.lastname: O'Higgins
authors.affiliation: School of Biological Sciences, Dublin Institute of Technology, Dublin 8, Republic of Ireland.
authors.forename: Shona
authors.initials: S
authors.lastname: Cawley
authors.affiliation: Department of Pediatrics, Trinity College, Dublin 2, Republic of Ireland.
authors.forename: Anne
authors.initials: A
authors.lastname: Doolan
authors.affiliation: School of Biological Sciences, Dublin Institute of Technology, Dublin 8, Republic of Ireland.
authors.forename: Daniel
authors.initials: D
authors.lastname: McCartney
authors.affiliation: UCD Centre for Human Reproduction, Coombe Women and Infants University Hospital, Dublin 8, Republic of Ireland.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Turner
mesh_terms: D000328:Adult; D015982:Bias; D003430:Cross-Sectional Studies; D002149:Energy Intake; D005260:Female; D006801:Humans; D011247:Pregnancy; D057566:Self Report
keywords: Willet food frequency questionnaire; energy intake; periconceptional; under-reporters