title: Perinatal Biochemical Confirmation of Smoking Status by Trimester.
abstract: BACKGROUND
  Tobacco use during pregnancy is the most modifiable risk factor associated with poor pregnancy outcomes. Self-reported tobacco use has been demonstrated to have high misclassification rates. The aims were to examine misclassification rates of perinatal tobacco use during each trimester of pregnancy and 8 weeks postpartum, and to evaluate characteristics associated with misclassification of tobacco use status.
  
  
  METHODS
  This is secondary analysis of a prospective, multicenter trial of pregnant women, and it includes participants who were biochemically identified as tobacco users during their first trimester (N = 103). Each trimester and once postpartum, tobacco use was assessed via self-report and validated using a cutoff of 100 ng/mL for urine cotinine via NicAlert test strips to indicate current use. Those who self-reported as nonusers but were identified as users via urine cotinine were considered misclassified; misclassification rates were determined for each time period. Logistic regression assessed maternal factors associated with misclassification status.
  
  
  RESULTS
  Misclassification rates declined from 35.0% at first trimester to 31.9% and 26.6% at the second and third; the postpartum rate was 30.4%. These rates did not differ significantly from each other at the 0.05 level. Race/ethnicity was associated with misclassification status; white/non-Hispanic women were 87% less likely to be misclassified (p < .001).
  
  
  CONCLUSIONS
  Misclassification of prenatal smoking status decreases as pregnancy progresses, though the observed rate change was not significant. Minority women may be at particular risk for non-disclosure of tobacco use. Biochemical validation should be considered when assessing perinatal tobacco use via self-report, given high misclassification rates throughout the perinatal period.
  
  
  CONCLUSIONS
  These results demonstrate that regardless of trimester, more than one-quarter of tobacco-using pregnant women may not disclose tobacco use throughout pregnancy and early postpartum. Although the rate of misclassification decreased from first to third trimester and then increased in the immediate postpartum, these changes in misclassification rates were not significant. Minority groups may be at particular risk of misclassification compared with white/non-Hispanic women. Biochemical validation is warranted throughout pregnancy to encourage cessation as tobacco use is one of the most easily-modified risk factors for poor birth outcomes.
authors.affiliation: University of Kentucky, College of Nursing, Lexington, KY.
authors.forename: Kristin
authors.initials: K
authors.lastname: Ashford
authors.affiliation: University of Kentucky, College of Nursing, Lexington, KY.
authors.forename: Amanda
authors.initials: A
authors.lastname: Wiggins
authors.affiliation: University of Georgia, Department of Infectious Diseases, Athens, GA.
authors.forename: Emily
authors.initials: E
authors.lastname: Rayens
authors.affiliation: University of Kentucky, College of Nursing, Lexington, KY.
authors.forename: Sara
authors.initials: S
authors.lastname: Assef
authors.affiliation: University of Kentucky, College of Nursing, Lexington, KY.
authors.forename: Amanda
authors.initials: A
authors.lastname: Fallin
authors.affiliation: University of Kentucky, College of Nursing, Lexington, KY.
authors.forename: Mary Kay
authors.initials: MK
authors.lastname: Rayens
mesh_terms: D000328:Adult; D003367:Cotinine / Q000652:urine*; D005006:Ethnicity / Q000706:statistics & numerical data*; D005260:Female; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D016015:Logistic Models; D049590:Postpartum Period / Q000652:urine; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First / Q000652:urine; D011262:Pregnancy Trimester, Second / Q000652:urine; D011263:Pregnancy Trimester, Third / Q000652:urine; D011446:Prospective Studies; D015203:Reproducibility of Results; D012307:Risk Factors; D057566:Self Report; D012907:Smoking / Q000453:epidemiology / Q000652:urine*; D044465:White People / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D003367:Cotinine