Comparing smoking topography and subjective measures of usual brand cigarettes between pregnant and non-pregnant smokers

Introduction: Most pregnant smokers report abruptly reducing their cigarettes per day (CPD) by ~50% after learning of pregnancy and making further smaller reductions over the remainder of their pregnancy. Laboratory and naturalistic studies with non-pregnant smokers have found that these types of reductions often lead to changes in smoking topography (i.e., changes in smoking intensity to maintain a desired blood-nicotine level). If pregnant women smoke more intensely, they may expose themselves and their offspring to similar levels of toxicants despite reporting reductions in CPD. Methods: Pregnant and non-pregnant female smokers (n = 20 and 89, respectively) participated. At the experimental session, after biochemical confirmation of acute abstinence, participants smoked one usual brand cigarette ad lib through a Borgwaldt CReSS Desktop Smoking Topography device. Carbon monoxide (CO) and measures of nicotine withdrawal, craving, and reinforcement derived from smoking were also collected. Results: The two groups did not differ on demographic or smoking characteristics at screening, except nicotine metabolism rate, which as expected, was faster in pregnant smokers. Analyses suggest that none of the smoking topography parameters differed between pregnant and nonpregnant smokers, although pregnant smokers had a significantly smaller CO boost. Both groups reported similar levels of relief of withdrawal and craving after smoking, but other subjective effects suggest that pregnant smokers find smoking less reinforcing than non-pregnant smokers. Conclusions: Pregnant smokers do not smoke cigarettes differently than non-pregnant women, but appear to find smoking comparatively less pleasurable. Implications: This is the first study to assess smoking topography in pregnant women. Pregnant women appear to be at increased risk for smoking cigarettes with more intensity because of (1) their tendency to make significant abrupt reductions in the number of cigarettes they smoke each day after learning of pregnancy and (2) an increase in nicotine metabolism induced by pregnancy. Despite these changes, the present results suggest that pregnant women do not smoke cigarettes more intensely or in a way that causes more toxicant exposure, perhaps due to a reportedly less pleasurable smoking experience.