Self-reported Smoking and Urinary Cotinine Levels among Pregnant Women in Korea and Factors Associated with Smoking during Pregnancy

This study examined urinary cotinine levels and self-reported smoking among pregnant women in Korea and the factors associated with smoking during pregnancy. The subjects were selected from pregnant women who visited 30 randomly sampled obstetric clinics and prenatal care hospitals in Korea in 2006. Smoking status was determined by self-reporting and urinary cotinine measurement. A total of 1,090 self-administered questionnaires and 1,057 urine samples were analyzed. The percentage of smoking revealed by self-reporting was 0.55% (95% confidence interval [CI], 0.11-0.99) and that revealed by urinary cotinine measurement (>100 ng/mL) was 3.03% (95% CI, 1.99-4.06). The kappa coefficient of agreement between self-reported smoking status and urinary cotinine measurement was 0.20 (95% CI, 0.03-0.37). Multiple logistic regression analysis revealed that early gestational period, low educational level, and being married to a smoker were significant risk factors for smoking during pregnancy. Smoking among pregnant women in Korea is not negligible, and those who are concerned to maternal and child health should be aware of this possibility among pregnant women in countries with similar cultural background.