Assessing nicotine metabolism in pregnancy—a novel approach using hair analysis

Metabolomics of Pregnancy Complications: Emerging Application of Maternal Hair

In recent years, the study of metabolomics has begun to receive increasing international attention, especially as it pertains to medical research. This is due in part to the potential for discovery of new biomarkers in the metabolome and to a new understanding of the "exposome", which refers to the endogenous and exogenous compounds that reflect external exposures. Consequently, metabolomics research into pregnancy-related issues has increased. Biomarkers discovered through metabolomics may shed some light on the etiology of certain pregnancy-related complications and their adverse effects on future maternal health and infant development and improve current clinical management. The discoveries and methods used in these studies will be compiled and summarized within the following paper. A further focus of this paper is the use of hair as a biological sample, which is gaining increasing attention across diverse fields due to its noninvasive sampling method and the metabolome stability. Its significance in exposome studies will be considered in this review, as well as the potential to associate exposures with adverse pregnancy outcomes. Currently, hair has been used in only two metabolomics studies relating to fetal growth restriction (FGR) and gestational diabetes mellitus (GDM).

Nicotine cut-off value in human hair as a tool to distinguish active from passive smokers: A cross-sectional study in Japanese men

BACKGROUND

Nicotine concentration in hair is a useful marker of tobacco exposure. Detection of nicotine in the hair of non-smokers indicates passive smoking. Accurate measurement of nicotine among active and passive smokers can help in smoking cessation programs or programs designed to prevent secondhand smoke exposure.

OBJECTIVE

To establish, using high-performance liquid chromatography-ultraviolet detection (HPLC/UV), a hair nicotine cut-off value to distinguish active from passive smokers.

METHODS

Hair samples were collected from randomly chosen Japanese men (n= 192) between 2009 and 2011. Nicotine and cotinine levels in hair were measured using HPLC/UV with column-switching. T-tests and chi-square tests were performed to compare active and passive smokers, while receiver operating characteristic curves were used to evaluate the effectiveness of the cut-off value.

RESULTS

There were 69 active smokers and 123 passive smokers. The nicotine and cotinine concentrations in hair were significantly higher in active than in passive smokers (p< 0.01). The area under the curve for nicotine was 0.92. A hair nicotine cut-off value of 5.68 ng/mg, with a sensitivity of 94.2% and specificity of 87.0%, was identified as the optimal cut-off value for separating active from passive smokers.

CONCLUSION

Nicotine and cotinine concentrations in hair clearly distinguished active from passive smokers.

Using nicotine in scalp hair to assess maternal passive exposure to tobacco smoke

Quantifying population exposure level to tobacco smoke is important for investigating its adverse effects on human health. We aimed to investigate the feasibility and application of using population hair concentrations of nicotine and cotinine to indicate their exposure level to tobacco smoke among pregnant women. Our study recruited 256 mothers who delivered healthy babies and collected their hair samples from scalp, of which 172 mothers were self-reported non-passive smokers and the other 84 mothers were self-reported passive smokers. We analyzed nicotine and cotinine concentrations of the hair section grown during the early pregnancy. The linear relationship between cotinine and nicotine was developed and validated by internal cross-validation method. Our results revealed that self-reported passive smokers had higher concentrations of nicotine [2.08 (1.00-4.46) ng/mg hair, i.e. median value (inter-quartile range)] and cotinine [0.063 (0.041-0.148) ng/mg hair] than non-passive smokers [1.35 (0.58-2.59) ng/mg hair of nicotine and 0.049 (0.022-0.087) ng/mg hair of cotinine, respectively]. There existed a linear regression model between hair cotinine and nicotine concentrations, i.e. [cotinine] = 0.024 × [nicotine]+0.0184 (R2 = 0.756) for this population. The internal cross-validation squared correlation coefficient slightly increased from 0.689 to 0.734 with the training subjects varying from 20% to 90%, suggesting that this regression model had high robustness and predictive accuracy. It was concluded that nicotine in maternal hair can evaluate the hair cotinine level and reflect maternal passive exposure level to ambient tobacco smoke with high sensitivity.

The Nicotine Metabolite Ratio in Pregnancy Measured by trans-3'-Hydroxycotinine to Cotinine Ratio: Characteristics and Relationship With Smoking Cessation

INTRODUCTION

Nicotine replacement therapy (NRT) helps nonpregnant smokers quit, but there is no evidence that standard dose NRT is effective in pregnancy. As nicotine metabolism increases in pregnancy, this could reduce NRT efficacy. Using the ratio of trans-3'-hydroxycotinine to cotinine, the nicotine metabolite ratio (NMR), we investigated relationships between the rate of nicotine metabolism, maternal characteristics and smoking cessation in pregnant women recruited to a randomized controlled trial of NRT.

METHODS

Data from 1,050 pregnant smokers in the Smoking, Nicotine and Pregnancy trial who were of 12-24 weeks gestation had exhaled carbon monoxide readings of ≥8 ppm at recruitment and who were randomized to NRT or placebo patches were used. Linear and logistic regression investigated associations between maternal characteristics and NMR and also between NMR and subsequent validated cessation from smoking.

RESULTS

Six hundred and sixty-two women (63%) provided blood samples for NMR estimation. Higher NMR was associated with increased cigarette consumption prior to pregnancy. At 1 month (odds ratio [OR] = 0.87; 95% CI = 0.76-0.99; p = .043) and delivery (OR = 0.79; 95% CI = 0.66-0.95; p = .010), there was a significant negative association between a 0.1 unit increase in NMR and odds of achieving cessation after adjusting for possible confounders. There was no evidence for an interaction between a 0.1 unit increase in NMR and treatment assignment on the odds of cessation at 1 month post-quit date (p = .556).

CONCLUSION

Pregnant women who metabolize nicotine more rapidly are less likely to achieve cessation when they try to quit smoking. There is no evidence that NRT is more effective in women who metabolize nicotine more slowly.

Prenatal tobacco exposure and cotinine in newborn dried blood spots

BACKGROUND

Tobacco smoking by pregnant women is a major public health hazard with both short- and long-term effects on offspring. This study describes the presence and level of the nicotine metabolite cotinine in newborn dried blood spots (DBS) and compares it with the reported maternal smoking recorded on state birth registries. We hypothesize that cotinine in DBS may be a useful measure of newborn in utero tobacco exposure.

METHODS

An observational, cross-sectional study of 1414 DBS obtained from California, Michigan, New York, and Washington newborn screening programs was carried out. Cotinine levels in DBS were quantified by liquid chromatography tandem mass spectrometry analysis and compared with maternal smoking as reported in vital statistics data.

RESULTS

Cotinine ≥0.3 ng/g was detected in 35% of newborn DBS, including DBS of 29% of newborns whose mothers reportedly did not smoke cigarettes during pregnancy, some of whom were presumably exposed to environmental tobacco smoke. Twelve percent of the newborn DBS had cotinine levels that were ≥9.0 ng/g (equivalent to 6 ng/mL plasma, a level that indicates active smoking of the mother), although 41% of the mothers of these infants reportedly did not smoke.

CONCLUSIONS

These data confirm that reported smoking during pregnancy is an imperfect measure of prenatal tobacco smoke exposure. Cotinine assessment in newborns may improve surveillance of tobacco use during pregnancy.

Tobacco smoke and pregnancy: segmental analysis of nicotine in maternal hair

The investigation assessed nicotine metabolism prior to and during pregnancy in relation to different maternal smoking habits. It included segmental hair analysis in 3 groups of postpartum women: 32 active smokers, 35 passive smokers, and 19 unexposed nonsmokers. Maternal hair at least 12 cm long was collected after delivery and was divided into four 3-cm-long segments representing each trimester of pregnancy and the 3 months prior to pregnancy. Hair nicotine concentration was determined by gas chromatography-mass spectrometry. Nicotine levels were the highest in the 3-month period before pregnancy and it gradually decreased with advancing gestation in all study groups. These results suggest that when assessing tobacco exposure as measured by nicotine in hair, metabolic changes of nicotine during pregnancy should be taken into consideration.

Association of self-reported passive smoking in pregnant women with cotinine level of maternal urine and umbilical cord blood at delivery

Passive smoking during pregnancy leads to adverse effects on mother and infant. The present investigation was designed to evaluate the association between maternal reported passive smoking with the cotinine concentration of maternal urine and umbilical cord blood at delivery and to determine the accuracy of maternal reporting of exposure to cigarette smoke during pregnancy. This was a cross-sectional study. From the 108 non-smoker pregnant women who were referred for delivery, 54 were passive smokers. Urine samples were collected from the mothers in the delivery room and blood samples after birth were taken from the umbilical cord. Passive smoking was evaluated through questionnaire and cotinine level of urine and umbilical cord blood. The geometric mean cotinine concentration of the maternal urine and the umbilical cord serum were, respectively, 27.4 ± 29.96 ng/mL and 3.71 ± 1.22 ng/mL in the exposed group (P < 0.001) and 0.75 ± 2.29 and 0.40 ± 0.63 in the non-exposed group (P < 0.001). There was a statistically significant correlation between maternal urinary and umbilical cord serum level of cotinine (P < 0.001, r = 0.58). Significant associations were shown between maternal reports of exposure to cigarette smoking with cotinine level of urine (kappa = 96%) and umbilical cord (kappa = 98%) (P < 0.001). This study shows that the pregnant woman's report of passive smoking during pregnancy in Iran is accurate. The questionnaire is an appropriate method to evaluate smoke exposure and could replace cotinine measurement.

Prenatal hair nicotine analysis in homes with multiple smokers

Prenatal exposure to secondhand smoke (SHS) is responsible for adverse perinatal outcomes, including preterm birth. Smoking at home is the primary source of exposure to women during pregnancy. Hair nicotine analysis of mothers and infants was used to describe the relationship between prenatal SHS exposure and number of household smokers. Maternal hair nicotine was strongly correlated with the number of household smokers and was a more sensitive measure of household smoking than infant hair. Home smoking bans and focused public media campaigns on the harmful effects of SHS exposure are necessary prevention strategies to avoid adverse perinatal outcomes.

Hair biomarkers as measures of maternal tobacco smoke exposure and predictors of fetal growth

INTRODUCTION

Most biomarker studies of the effects of maternal smoking on fetal growth have been based on a single blood or urinary cotinine value, which is inadequate in capturing maternal tobacco exposure over the entire pregnancy. We used hair biomarkers to compare the associations of maternal self-reported smoking, hair nicotine, and hair cotinine with birth weight for gestational age (BW for GA) among active and passive smokers during pregnancy.

METHODS

We collected maternal hair in the immediate postpartum period and measured nicotine and cotinine concentrations averaged over the pregnancy in 444 term controls drawn from 5,337 participants in a multicenter nested case-control study of preterm birth. BW for GA Z-score and small for gestational age (SGA) were based on Canadian population-based standards.

RESULTS

The addition of hair nicotine to multiple linear regression models containing self-reported active smoking, hair cotinine, or both explained significantly more variance in the BW for GA Z-score (p = .01, .03 and .04, respectively). Similarly, women with hair nicotine, but not cotinine, at or above the median value had a significant increase in the risk of SGA birth (odds ratio: 3.07, 95% CI: 1.25-7.52). No significant association was observed between maternal passive smoking and BW for GA based on hair biomarkers.

CONCLUSIONS

Hair nicotine is a better predictor of reductions in BW for GA than either hair cotinine or self-report. Our negative results for passive smoking suggest that previously reported small but significant effects may be explained by misclassification of active smokers as passive smokers based on self-report.

Smoking prevalence in early pregnancy: comparison of self-report and anonymous urine cotinine testing

OBJECTIVE

Societal pressures against smoking during pregnancy may lead to a reduction in disclosure of smoking status. The objective of this study was to compare prevalence of smoking at prenatal intake by self-report with anonymous biochemical validation.

METHODS

Women receiving care at the Duke Obstetrics Clinic from February 2005 through January 2006 were eligible for evaluation. Self-reported smoking and urine samples were obtained anonymously at prenatal intake. The NicCheck™ I semi-quantitative dipstick was used to detect urinary nicotine, cotinine, and 3-hydroxycotinine. The difference, with 95% confidence interval, between the proportions of smokers by self-report and urine testing was calculated for (1) high-positive vs. low-positive and negative results combined and (2) any positive vs. negative results.

RESULTS

Among 297 subjects, self-reported smoking was 18.2 vs. 14.8% for low-positive and negative results combined with an absolute difference of 3.4%, [-2.9%, 9.6%]. When comparing self-report with any positive result (43.1%), the absolute difference was 24.9%, [17.4%, 32.1%].

CONCLUSIONS

Our findings suggest that most pregnant women disclose their smoking and many nonsmokers may have significant second-hand exposure. Universal urinary cotinine screening of pregnant women could aid in appropriately counseling women about second-hand exposure as well as monitoring women at high risk for adverse pregnancy outcomes.

Assessing the accuracy of self-reported smoking status and impact of passive smoke exposure among pregnant Aboriginal and Torres Strait Islander women using cotinine biochemical validation

INTRODUCTION AND AIMS

A significant level of misreport or error occurs during questionnaire-based assessment of smoking behaviour. Failure to measure environmental tobacco smoke, and participant's inclination to under-report their smoking raise questions as to the accuracy of assessment. In order to establish an estimation of the possible error associated with such assessment, the accuracy of self-reported smoking status among a group of pregnant Aboriginal and Torres Strait Islander women was examined.

DESIGN AND METHODS

Women attending two Aboriginal Medical services in Far North Queensland for antenatal care were invited to participate. Women completed an interviewer assisted questionnaire relating to their smoking status and a 24 h diary of their exposure to nicotine and consumption of alcohol. Urine samples were analysed for cotinine using an Enzyme Linked Immunosorbent Assay.

RESULTS

Cotinine analysis indicated that 17% of women who reported that they were non-smokers were likely to have misreported this status, or be exposed to high levels of passive smoke. The only significant predictors of cotinine level were self-reported nicotine exposure (including passive smoke) and number of cigarettes smoked in the previous 24 h. Other individual and environmental variables had no significant influence on cotinine level using this analysis technique.

DISCUSSION AND CONCLUSIONS

The level of potential error in smoking assessment among this group was substantial. Exposure to environmental tobacco smoke might explain part of this error, but the reasons for misreport can only be speculated. This rate of misclassification should be taken into consideration in routine screening of antenatal women in primary health care.

Measuring prenatal secondhand smoke exposure in mother-baby couplets

INTRODUCTION

Pregnant women often underreport their smoking status and extent of secondhand smoke (SHS) exposure. Biomarker confirmation is the recommended method to assess smoking behaviors and SHS exposure in both mothers and infants.

OBJECTIVES

The primary aims are to (a) examine the relationship between smoking behaviors and SHS exposure in mother-baby couplets using maternal and infant hair nicotine and maternal urine cotinine analyses and (b) determine whether there is an association between maternal and infant hair nicotine samples obtained shortly after birth.

DISCUSSION

A cross-sectional study with a multiethnic sample of 210 mother-baby couplets assessing SHS exposure.

RESULTS

The level of maternal hair nicotine (MHN) was significantly different among three groups: nonsmoking, nonsmoking/passive exposed, and smoking (p < .0001), with nonsmoking and nonexposed women having the lowest level. Urine cotinine was strongly associated with self-reported smoking status (rho = .88; p < .0001). Maternal and infant hair nicotine were correlated, although MHN correlated more strongly with smoking status (rho = .46, p < .0001) than infant hair nicotine (rho = .39, p < .0001).

CONCLUSIONS

MHN was a more precise biomarker of prenatal SHS exposure than infant hair nicotine; mothers' urine cotinine was strongly correlated with self-reported smoking status.

Determination of hair nicotine by gas chromatography-mass spectrometry

Hair nicotine is a known biomarker for monitoring long-term environmental tobacco smoke (ETS) exposure and smoking status. In general, hair nicotine assay involves alkaline digestion, extraction and instrumental analysis. The gas chromatography-mass spectrometry (GC-MS) assay currently developed has shown to be of high throughput with average approximately 100 hair samples being extracted and analyzed per day. This was achieved through simplified extraction procedure and shortened GC analysis time. The extraction was improved by using small volume (0.4 mL) of organic solvent that does not require further evaporation and salting steps prior to GC-MS analysis. Furthermore, the amount of hair utilized in the extraction was very little (5 mg) while the sensitivity and selectivity of the assay is equal, if not better than other established methods. The linearity of the assay (r(2)>0.995), limit of quantitation (0.04 ng/mg hair), within- and between-assays accuracies and precisions (<11.4%) and mean recovery (92.6%) were within the acceptable range.

Neonatal hair nicotine levels and fetal exposure to paternal smoking at home

Exposure to environmental tobacco smoke (ETS) is a major risk to human health, and the home is the greatest single source of ETS for children. The authors investigated fetal exposure to paternal smoking at home during pregnancy. Korean families were included as trios of fathers, mothers, and neonates identified in 2005-2007. Sixty-three trios were finally enrolled in this study after exclusion of those in which the mother was a smoker or was regularly exposed to ETS at places other than the home. Nicotine and cotinine concentrations in hair were measured by using liquid chromatography-tandem mass spectrometry to determine long-term exposure to ETS. The difference between neonatal nicotine concentrations in the smoker and nonsmoker groups was not statistically significant. However, in the indoor-smoker group, neonatal nicotine concentrations were significantly higher than in the outdoor and nonsmoker groups (P < 0.05). Furthermore, neonatal nicotine concentrations in the outdoor-smoker group were not different from those in the nonsmoker group. These findings indicate that paternal smoking inside the home leads to significant fetal and maternal exposure to ETS and may subsequently affect fetal health. Conversely, findings show that paternal smoking outside the home prevents the mother and her fetus from being exposed to ETS.

Novel methods for the detection of drug and alcohol exposure during pregnancy: implications for maternal and child health

Despite extensive evidence of fetal and neonatal risk, a large number of pregnant women are involved in excessive alcohol and drug abuse, such as with cocaine, methamphetamine, opioids, and cannabinoids.

Analytical pitfalls in hair testing

This review focuses on possible pitfalls in hair testing procedures. Knowledge of such pitfalls is useful when developing and validating methods, since it can be used to avoid wrong results as well as wrong interpretations of correct results. In recent years, remarkable advances in sensitive and specific analytical techniques have enabled the analysis of drugs in alternative biological specimens such as hair. Modern analytical procedures for the determination of drugs in hair specimens - mainly by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) - are reviewed and critically discussed. Many tables containing information related to this topic are provided.

Neonatal urinary cotinine correlates with behavioral alterations in newborns prenatally exposed to tobacco smoke

Altered behavior due to prenatal smoke exposure was examined in 25 neonates born from smoking mothers who consumed at least 5 cigarettes/d during the entire gestation. Data were compared with 25 matched neonates born from nonsmoking mothers. Neonatal behavior was evaluated using the Brazelton Neonatal Behavioral Assessment Scale (BNBAS). Antenatal exposure to tobacco smoke at the end of the pregnancy was determined by measurement of urinary cotinine. Newborns from smoking mothers showed significant lower scores in various BNBAS items compared with neonates from nonsmoking mothers. A strong correlation was observed between infant irritability and urinary cotinine in newborns from smoker and nonsmoking mothers and with number of daily smoked cigarettes and maternal nicotine daily intake of infants exposed to active maternal smoking. Linear regression analysis showed that urinary cotinine was the best predictor of infant irritability (r(2) = 0.727). The latter was also associated to the neonate's low level of attention and poor response to inanimate auditory stimuli. Among infants from nonsmoking mothers, paternal smoking significantly correlated with infant urinary cotinine and infant irritability, being also the best predictor of irritability (r(2) = 0.364). Neonatal behavior can be significantly altered in a dose-dependent manner even after modest prenatal exposure to tobacco smoke.

In utero exposure to smoking and newborn neurobehavior: how to assess neonatal withdrawal syndrome?

Recent studies postulate neurotoxic effects of prenatal tabacco exposure, passive addiction, and neonatal nicotine withdrawal syndrome in newborns in utero exposed to maternal smoking. The neonatal withdrawal syndrome is characterized by irritability, tremors, and sleep disturbances, most typically observed in newborns of heavy smoking mothers.

TDM Grand Rounds: Neonatal Nicotine Withdrawal Syndrome in an Infant Prenatally and Postnatally Exposed to Heavy Cigarette Smoke

A heavy smoking, lactating mother delivered a baby that exhibited spontaneous tremors, fluctuations of muscular rigidity, and opisthotonus at 48 hours of life. Although the symptoms did not disappear within the following days, they could be controlled by swaddling or wrapping the baby in a blanket. The absence of any other etiology generated a suspicion of prenatal exposure to heavy tobacco smoke and potential neonatal nicotine withdrawal syndrome. This diagnosis was supported by extremely high concentration of hair nicotine and cotinine in the infant's hair and in different segments of maternal hair. The presence of non-negligible amounts of nicotine and cotinine in breast milk confirmed that the mother did not quit smoking after delivery, despite her reports. The breast-fed newborn continued to have 3 to 4 crises of spontaneous tremors and alternant muscular rigidity per day for a month. More studies are needed to establish neonatal nicotine withdrawal.

The study of metabolite-to-parent drug ratios of methamphetamine and methylenedioxymethamphetamine in hair

The metabolite-to-parent drug ratios were determined in the hair of 2444 methamphetamine (MA) abusers who had produced MA-positive hair results from 2001 to May 2005 and in the hair of 53 ecstasy abusers who had produced positive methylenedioxymethamphetamine (MDMA) hair results from 2002 to May 2005. For the hair analyses, hair strands were washed, cut into small pieces and extracted for 20 h in 1 mL methanol containing 1% HCl. Drugs in the extract were determined by gas chromatography-mass spectrometry (GC-MS) using selective ion monitoring after derivatization with trifluoroacetic anhydride. The six range groups were divided as follows on the basis of MA concentrations in hair (n = 2389): 0.5-5 ng/mg (n = 950), 5-10 ng/mg (n = 582), 10-20 ng/mg (n = 503), 20-30 ng/mg (n = 160), 30-40 ng/mg (n = 80), more than 40 ng/mg (n = 114) to assess the correlations between MA concentrations and metabolite-to-parent drug ratios. In groups of higher MA concentrations, lower ratios of AP/MA were found, and there was a statistically significant difference among six range groups. Comparisons of age groups (tens, twenties, thirties, forties, fifties, and sixties) and male and female subjects for the ratios of AP/MA showed a statistically significant difference. The detection of metabolites and the parent drug with reasonable ratios was found to be a useful indicator for distinguishing internal drug incorporation from external contamination. In our study, MA users can produce 0.4-116% (mean = 9%) of amphetamine (AP) concentrations in hair, and ecstasy users 1-110% (mean = 12%) of methylenedioxyamphetamine (MDA) in appropriately washed hair samples.

State of the art in hair analysis for detection of drug and alcohol abuse

Hair differs from other materials used for toxicological analysis because of its unique ability to serve as a long-term storage of foreign substances with respect to the temporal appearance in blood. Over the last 20 years, hair testing has gained increasing attention and recognition for the retrospective investigation of chronic drug abuse as well as intentional or unintentional poisoning. In this paper, we review the physiological basics of hair growth, mechanisms of substance incorporation, analytical methods, result interpretation and practical applications of hair analysis for drugs and other organic substances. Improved chromatographic-mass spectrometric techniques with increased selectivity and sensitivity and new methods of sample preparation have improved detection limits from the ng/mg range to below pg/mg. These technical advances have substantially enhanced the ability to detect numerous drugs and other poisons in hair. For example, it was possible to detect previous administration of a single very low dose in drug-facilitated crimes. In addition to its potential application in large scale workplace drug testing and driving ability examination, hair analysis is also used for detection of gestational drug exposure, cases of criminal liability of drug addicts, diagnosis of chronic intoxication and in postmortem toxicology. Hair has only limited relevance in therapy compliance control. Fatty acid ethyl esters and ethyl glucuronide in hair have proven to be suitable markers for alcohol abuse. Hair analysis for drugs is, however, not a simple routine procedure and needs substantial guidelines throughout the testing process, i.e., from sample collection to results interpretation.