Abstract
INTRODUCTIONTobacco use remains the single most modifiable cause of adverse pregnancy outcomes. It is crucial to be able to accurately quantify the burden of tobacco exposure on both the mother and fetus to have better measures of efficacy with interventions being studied.METHODSThis is a descriptive and exploratory study conducted within a randomized controlled trial. Pregnant smoking and non-smoking women were followed from ≤22 weeks’ gestation through delivery with monthly maternal smoking questionnaires, urine cotinine levels, and collection of maternal and infant hair and nail samples, at delivery. Nicotine was extracted and measured (ng/mg) using high-performance liquid chromatography with electrochemical detection.RESULTSForty-six mother–infant dyads (34 pregnant smokers and 12 pregnant non-smokers) had successful completion of maternal and infant hair and nails samples. The median hair nicotine levels of the smoking mothers and their infants was significantly higher than those of the non-smokers (1.015 vs 0.037 ng/ mg, p<0.05 for the mothers; 0.445 vs 0.080 ng/mg, p<0.01 for the infants). Similarly, the median nail nicotine levels for smoking mothers and their infants were significantly higher than the non-smokers (2.130 vs 0.056 ng/mg, p<0.01 for the mothers; 0.594 vs 0.132 ng/mg, p<0.05 for the infants). We found a moderate but significant correlation between maternal hair and nail nicotine (r=0.64, p<0.001), infant hair and nail nicotine (r=0.64; p<0.001), maternal and infant hair nicotine (r=0.61, p<0.001), and maternal and infant nail nicotine levels (r=0.58, p<0.001).CONCLUSIONSOur study shows that both infant hair and nail nicotine levels are valid biomarkers of intrauterine tobacco smoke exposure, and can be used to identify prenatal smoke exposure, correlating well with the level of maternal nicotine exposure.
Highlights
Tobacco use remains the single most modifiable cause of adverse pregnancy outcomes
Our study aims to demonstrate that infant hair and nail nicotine levels collected shortly after birth correlate with maternal hair and nail nicotine levels and reflect maternal cigarette/nicotine exposure during pregnancy
Study participants were recruited from prenatal clinics at: Oregon Health & Science University (OHSU) and Providence Maternal Care Clinic in Portland, Oregon; and Vancouver Clinic and PeaceHealth Southwest Medical in Vancouver, Washington; who were aged ≥15 years, current smokers (≥1 cigarette/day), with singleton gestation, randomization at ≤22 weeks’ gestation age (GA) by last menstrual period (LMP), and had declined smoking cessation attempts as discussed by their physician and study personnel
Summary
It is crucial to be able to accurately quantify the burden of tobacco exposure on both the mother and fetus to have better measures of efficacy with interventions being studied. Tobacco use remains the single most modifiable cause of adverse pregnancy outcomes, yet, more than 50% of smokers who become pregnant continue to smoke[1,2]. In our randomized placebo-controlled trial of pregnant women who smoke, we reported urine cotinine as our biomarker for maternal smoking status, but to our knowledge, no other study has collected maternal and infant hair and nail samples at delivery alongside a prospective collection of serial maternal smoking questionnaires and urine cotinine levels for the duration of the pregnancy, to determine if nicotine in infant hair and nail could be reliable biomarkers of in-utero exposure to tobacco smoke[18]. Our study aims to demonstrate that infant hair and nail nicotine levels collected shortly after birth correlate with maternal hair and nail nicotine levels and reflect maternal cigarette/nicotine exposure during pregnancy
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