This found a statistically though significant relationship between increasing FTCD scores and urinary cotinine concentrations. The other study (Albrecht et al., 1999) found a significant relationship between increasing FTQ scores and salivary cotinine levels in 42 pregnant adolescents recruited from three different smoking cessation studies. Although these studies suggest that both questionnaire-based measures may have some validity for measuring nicotine addiction in pregnancy, their sample sizes were small and more evidence is needed, particularly regarding the utility of the HSI in pregnancy. Cotinine is the primary metabolite of nicotine and is often used as an objective biochemical measure of nicotine exposure to investigate validity of nicotine dependence measures (Benowitz, Hukkanen, & Jacob, 2009; Tricker, 2006).

Cotinine levels can be measured in blood or saliva samples; however, the relationship between blood and salivary cotinine in pregnancy remains unclear due to the changes in nicotine metabolism (Dempsey, Jacob, & Benowitz, 2002; Rebagliato et al., 1998) and saliva composition during gestation (Eliasson, Birkhed, Osterberg, & Carl��n, 2006; Guidozzi, Maclennan, Graham, & Jooste, 1992; Laine et al., 1988). Epidemiological studies of nonpregnant smokers found that mean salivary cotinine levels are closely related to serum cotinine but are around 25% higher (Jarvis, Primatesta, Erens, Feyerabend, & Bryant, 2003).

Quantification of the relationship in pregnancy would enable researchers to compare findings from studies of pregnant smokers, which use either serum or saliva samples and would permit researchers the flexibility to be pragmatic when deciding whether to use saliva or blood samples for cotinine estimation in research studies (Tricker, 2006). We aimed to investigate the validity of HSI as nicotine dependence measure in pregnancy by comparing this to three biochemical measures of nicotine and smoking exposure: blood cotinine, salivary cotinine, and exhaled carbon monoxide (CO); and we also investigated the relationship between blood and salivary cotinine samples taken simultaneously from pregnant smokers. METHODS Data for analyses in this report were collected at baseline in the Smoking, Nicotine and Pregnancy (SNAP) multicenter randomized trial that investigated the efficacy and safety of nicotine replacement patches in pregnancy (Coleman et al.

, 2012). Full methods and the study protocol were published Anacetrapib elsewhere (Coleman et al., 2012, 2007). Sample Population From May 2007 to February 2010, 1,050 pregnant women who attended antenatal ultrasonography appointments at seven hospital sites in East Midlands, England, were recruited. Trial participants were pregnant smokers aged 16�C46 years and 12�C24 weeks of gestation. They smoked 10 or more cigarettes daily before pregnancy and five or more cigarettes daily at trial enrolment, as well as provided an exhaled CO sample of at least 8 ppm.