title: Accurate reporting of expected delivery date by mothers 9 months after birth.
abstract: OBJECTIVE
  To measure agreement between gestational age based on maternal report of expected date of delivery (EDD) 9 months after birth and gestational age at birth in routine hospital data. Furthermore, to examine whether sociodemographic and perinatal factors influenced agreement and whether disagreement affected classification of infants in preterm groups.
  
  
  METHODS
  The study used data on 8,058 singleton infants from the UK Millennium Cohort Study. Women were interviewed 9 months after birth and interviews were linked to routine hospital data. The infant's date of birth and EDD were used to calculate gestational age in completed weeks.
  
  
  RESULTS
  Agreement between maternal report and hospital data was 72% for exact number of weeks' gestation and 94% for agreement within 1 week. Disagreement was associated with the infant not being firstborn, unplanned pregnancy, late or no antenatal care, and low socioeconomic status. Maternal report of gestational age resulted in slightly more children being classified as preterm (6.4%) than gestational age based on hospital data (6.1%). Agreement was found to be poor for postterm births.
  
  
  CONCLUSIONS
  Gestational age based on retrospective maternal reporting of EDD is reliable within 1 week or when used to assign infants to broad gestational groups.
authors.affiliation: National Perinatal Epidemiology Unit, University of Oxford, Old Road Campus, Oxford OX3 7LF, UK. gry.poulsen@npeu.ox.ac.uk
authors.forename: Gry
authors.initials: G
authors.lastname: Poulsen
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Kurinczuk
authors.forename: Dieter
authors.initials: D
authors.lastname: Wolke
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Boyle
authors.forename: David
authors.initials: D
authors.lastname: Field
authors.forename: Zarko
authors.initials: Z
authors.lastname: Alfirevic
authors.forename: Maria A
authors.initials: MA
authors.lastname: Quigley
mesh_terms: D000328:Adult; D015331:Cohort Studies; D036861:Delivery, Obstetric / Q000523:psychology / Q000706:statistics & numerical data*; D005260:Female; D005865:Gestational Age; D006753:Hospital Records / Q000592:standards / Q000706:statistics & numerical data*; D006801:Humans; D007231:Infant, Newborn; D011939:Mental Recall; D009035:Mothers / Q000523:psychology / Q000706:statistics & numerical data*; D015588:Observer Variation; D011203:Poverty; D011247:Pregnancy; D012307:Risk Factors; D057566:Self Report; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D006113:United Kingdom / Q000453:epidemiology