Smoking prevalence in early pregnancy: comparison of self-report and anonymous urine cotinine testing

J Matern Fetal Neonatal Med. 2011 Jan;24(1):86-90. doi: 10.3109/14767051003758887. Epub 2010 Apr 12.


Objective: Societal pressures against smoking during pregnancy may lead to a reduction in disclosure of smoking status. The objective of this study was to compare prevalence of smoking at prenatal intake by self-report with anonymous biochemical validation.

Methods: Women receiving care at the Duke Obstetrics Clinic from February 2005 through January 2006 were eligible for evaluation. Self-reported smoking and urine samples were obtained anonymously at prenatal intake. The NicCheck™ I semi-quantitative dipstick was used to detect urinary nicotine, cotinine, and 3-hydroxycotinine. The difference, with 95% confidence interval, between the proportions of smokers by self-report and urine testing was calculated for (1) high-positive vs. low-positive and negative results combined and (2) any positive vs. negative results.

Results: Among 297 subjects, self-reported smoking was 18.2 vs. 14.8% for low-positive and negative results combined with an absolute difference of 3.4%, [-2.9%, 9.6%]. When comparing self-report with any positive result (43.1%), the absolute difference was 24.9%, [17.4%, 32.1%].

Conclusions: Our findings suggest that most pregnant women disclose their smoking and many nonsmokers may have significant second-hand exposure. Universal urinary cotinine screening of pregnant women could aid in appropriately counseling women about second-hand exposure as well as monitoring women at high risk for adverse pregnancy outcomes.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Anonymous Testing
  • Cotinine / urine*
  • Female
  • Humans
  • Pregnancy / statistics & numerical data*
  • Pregnancy / urine
  • Prevalence
  • Self Report*
  • Smoking / epidemiology*
  • Tobacco Smoke Pollution
  • Young Adult


  • Tobacco Smoke Pollution
  • Cotinine