Self-reported cigarette smoking status imprecisely quantifies exposure in pregnancy

Abstract

Objective: We sought to determine the validity of self-reported smoking activity versus two quantitative measurements of tobacco exposure in pregnancy. We hypothesized that pregnant women would under-report their daily smoking amounts, due to the negative social stigmas associated with such a behavior. Methods: Cigarette-smoking and non-smoking pregnant women were recruited as part of a larger research study. Pregnant women with a singleton baby (>24 weeks) were recruited at a clinical appointment or prior to an elective caesarian section. Self-reported smoking status, including time since last cigarette, was recorded. End-tidal breath carbon monoxide (ETCO) levels and urine cotinine levels were measured and compared. Results: Both normotensive non-smoking (NTN) (n = 44) and normotensive smoking (NTS) (n = 24) pregnant women were recruited. A strong correlation was found between ETCO levels and urine cotinine measurements (r = 0.6566, p < 0.05). Self-reported smoking status in NTS was poorly correlated with ETCO levels (r = 0.5356, p < 0.05) and urine cotinine levels (r = 0.0324, P > 0.05). Conclusion: Self-reported smoking status accurately identifies women who smoke in pregnancy, but not their level of tobacco exposure. Urine cotinine or ETCO are much better quantitative measurements of nicotine and carbon monoxide, respectively, and should be measured for a more precise indicator of smoking activity. These devices will allow for better counseling and monitoring of women who are trying to quit smoking and/or who enter into smoking cessation programs

Maternal smoking during pregnancy and offspring overweight: is there a dose–response relationship? An individual patient data meta-analysis

“…Good markers for early pregnancy smoke exposure are required. End-tidal breath carbon monoxide levels and urine cotinine levels in the mother do provide more accurate measurements for recent nicotine and carbon monoxide exposure [77], but may indicate transient exposures rather than chronicity during pregnancy. Substantial within-person fluctuation may exist if women repeatedly try to quit or cutdown.…”

Psychosocial interventions for supporting women to stop smoking in pregnancy

“…A degree of misclassification is not surprising given the social stigma associated with smoking in pregnancy, and there appears to be less misclassification in non-pregnant populations (Patrick 1994). Some studies suggest that measurement of abstinence is reasonably accurate, but that there is greater inconsistency with reporting the amount of cigarettes smoked (Klebanoff 1998; Venditti 2012). Given this potential for bias, biochemical validation of smoking abstinence is now the standard for smoking cessation studies (West 2005; Shipton 2009).…”

Chronic carbon monoxide inhalation during pregnancy augments uterine artery blood flow and uteroplacental vascular growth in mice

“…The main difference is observed in the combustible elements of cigarette smoking, as nicotine and other components of these tobacco products are similar between them. Carbon monoxide (CO) is one such product of combustion found in cigarettes that is increased in the blood and end-tidal breath of those who smoke (52), yet decreased in the end-tidal breath systems of women who develop PE (29).…”