Cord serum cotinine as a biomarker of fetal exposure to cigarette smoke at the end of pregnancy.

Abstract

This study investigated the association between biomarkers of fetal exposure to cigarette smoke at the end of pregnancy, cotinine in cord serum and in maternal and newborn urine samples, and quantitative measurement of smoking intake and exposure evaluated by maternal self-reported questionnaire. Study subjects were 429 mothers and their newborns from a hospital in Barcelona, Spain. A questionnaire including smoking habits was completed in the third trimester of pregnancy and on the day of delivery. Cotinine concentration in cord serum was associated with daily exposure to nicotine in nonsmokers and with daily nicotine intake in smokers. The geometric mean of cotinine concentration in cord serum statistically discriminated between newborns from nonexposed and exposed nonsmoking mothers, and between these two classes and smokers, and furthermore was able to differentiate levels of exposure to tobacco smoke and levels of intake stratified in tertiles. Urinary cotinine levels in newborns from nonsmoking mothers exposed to more than 4 mg nicotine daily were statistically different from levels in two other categories of exposure. Cotinine concentration in urine from newborns and from mothers did not differentiate between exposure and nonexposure to environmental tobacco smoke (ETS) in nonsmoking mothers. Cord serum cotinine appeared to be the most adequate biomarker of fetal exposure to smoking at the end of pregnancy, distinguishing not only active smoking from passive smoking, but also exposure to ETS from nonexposure.

Fetal exposure to tobacco smoke is common

“…This prevalence of active smoking during pregnancy is noticeably higher than in many European countries,3 4 or USA 5. Furthermore, of the remaining 275 cord blood samples coming from non-smoker mothers reporting both exposure and non-exposure to environmental smoke during pregnancy, 83% presented cotinine levels above 1 ng/ml, a cut off used to distinguish exposure from no exposure to environmental tobacco smoke 2. This finding indicates a universal fetal exposure to cigarette smoke at least during the last days of pregnancy.…”

Transgenerational Exposure to Environmental Tobacco Smoke

“…COT but not NIC concentrations in mothers’ plasma, breast milk, and infants’ urine reflected the smoking habits during pregnancy [43]. However, in other studies this relationship was not corroborated, after studying 429 mothers and their newborns, measuring COT concentrations in neonatal urine and cord serum [42]. Recently, meconium became the specimen of choice for detecting drug exposure in neonates.…”

Smoking during pregnancy and postpartum among Tunisian women

“…Misclassification of smoking status by pregnant women could have resulted from the heightened awareness related to the hazards of smoking during pregnancy and the desire to provide a socially desirable response [22,32]. Because smoking presents a danger to the fetus as well as to the women themselves, they may be more reluctant to reveal their true smoking status [33,34]. The category of nonsmokers with high cotinine levels may include former smokers who have recently stopped smoking [34].…”

“…Because smoking presents a danger to the fetus as well as to the women themselves, they may be more reluctant to reveal their true smoking status [33,34]. The category of nonsmokers with high cotinine levels may include former smokers who have recently stopped smoking [34]. Because of the half-life of serum cotinine, the self-reported nonsmoker with a high cotinine level should regard herself as a former smoker if she stopped smoking 2 or 3 days earlier [20].…”