Smoking during pregnancy measured by population cotinine testing

N Z Med J. 1997 Aug 22;110(1050):311-4.


Aim: To establish a baseline cross-sectional prevalence of maternal smoking, measured by antenatal serum cotinine testing, in a population of pregnant women.

Methods: Residual sera from first and second routine antenatal blood samples were collected anonymously over a six-month period for pregnancies within the Canterbury region. Cotinine levels were measured by an ELISA test with a result of > 14 ng/mL indicative of active smoking. Only pregnancies ending in a confirmed live birth were considered in smoking prevalence calculations. There was a total of 1948 eligible residual blood samples.

Results: Of the 414 residual blood samples available for the first two months of pregnancy, 146 (35.3%) were found to be positive for cotinine. Smoking prevalence decreased over pregnancy so that by the third trimester 225 (26.8%) of 838 samples were cotinine positive. Infants born from smoking mothers had significantly lower birth weights.

Conclusions: In 1994, a third of women tested in early pregnancy and a quarter of women tested in late pregnancy were identified as being smokers. Repeated objective cross-sectional surveys will allow accurate assessment of the efficacy of smokefree interventions both before and during pregnancy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Birth Weight
  • Cotinine / blood*
  • Cross-Sectional Studies
  • Female
  • Gestational Age
  • Humans
  • New Zealand / epidemiology
  • Pregnancy / blood*
  • Pregnancy Trimester, First / blood
  • Pregnancy Trimester, Third / blood
  • Prevalence
  • Smoking / epidemiology*


  • Cotinine