Fetal exposure to tobacco: nicotine and cotinine concentration in amniotic fluid and maternal saliva

Abstract

Objective: Fetal exposure to tobacco constituents is a risk factor for negative birth outcomes. We aimed to determine the relationships between nicotine and cotinine concentrations in amniotic fluid and maternal saliva.

Methods: As part of a therapeutic trial, 42 pregnant smokers agreed to sample amniotic fluid (8 samples from amniocentesis, 34 at birth). Their smoking characteristics were collected along with the newborns’ birth outcomes.

Results: The median concentrations [IQR] in amniotic fluid and saliva were 11 [7–31] and 38 [7–174] μg/L for nicotine and 72 [22–123] μg/L and 55 [17–109] μg/L for cotinine, respectively. Multivariate models showed that saliva cotinine concentration predicted amniotic fluid nicotine and cotinine concentrations (R²=0.398, p < 0.0001 and R²=0.708, p < 0.0001 respectively). Amniotic fluid nicotine or cotinine concentration was not associated with birth weight. In multivariate analysis, the time elapsed since the last cigarette was the only variable associated with increased birth weight (R²=0.237, p = 0.002).

Conclusions: Maternal saliva sampling for the determination of cotinine concentration is of interest to monitor fetal exposure to nicotine of any origin. Nevertheless, the time elapsed since the last cigarette was a better predictor of birth weight than the biomarkers’ concentrations in amniotic fluid or maternal saliva.

• Birth weight
• maternal smoking during pregnancy
• prenatal tobacco exposure

Acknowledgements

The authors thank Martine Guimard for her skillful technical assistance. They also wish to thank the study participants and the medical staff at the participating maternity wards: Nathalie Hochedé, Martine Breton, Marie-Christine Pavia, the midwives and Drs Fabienne Bottet and Catherine Wiart. The pregnant smokers gave written informed consent at the time of the inclusion visit, and an informed written consent form also was signed by the father of the child-to-be-born to allow the recording of the newborn’s data, as required by French law on biomedical research.

Ethical approval

The pregnant smokers were participants of a randomized, placebo controlled, multicentre efficacy trial of nicotine patches (Identifier: ClinicalTrials.gov NCT00507975). The study protocol had been approved by the Ethics Committee of Groupe Hospitalier Pitié-Salpêtrière, Paris, France on March 26, 2007.

Declaration of interest

The authors report no conflicts of interest. Nelly Jacob, Jean-Louis Golmard and Ivan Berlin have no financial relationships relevant to this article to disclose. The Ministry of Health and Assistance Publique-Hôpitaux de Paris had no role in the design and conduct of the study, in the collection, analysis and interpretation of the data and in the preparation of the manuscript. N. Jacob is an employee of Assistance Publique-Hôpitaux de Paris, JL. Golmard and I. Berlin are employes of Assistance Publique-Hôpitaux de Paris and Université P. & M. Curie.

The study was funded by the Ministry of Health, France (grant number MA05 00150) and co-sponsored by Assistance Publique-Hôpitaux de Paris (grant number P060604).

Supplementary material available online