The effectiveness of nicotine replacement therapy during pregnancy: investigating the role of nicotine substitution, nicotine metabolism and pregnant smokers’ experiences

Bowker, Katharine (2016) The effectiveness of nicotine replacement therapy during pregnancy: investigating the role of nicotine substitution, nicotine metabolism and pregnant smokers’ experiences. PhD thesis, University of Nottingham.

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Nicotine replacement therapy (NRT) is effective in non-pregnant populations at assisting smoking cessation, but there is no evidence that NRT can help pregnant smokers to stop. Nicotine metabolism increases during pregnancy, and so the nicotine dose delivered by NRT could be insufficient for ameliorating withdrawal symptoms. However, little is known about the level of nicotine substitution provided by NRT or the pattern of nicotine metabolism during pregnancy. Also low adherence to NRT may explain why NRT does not appear to be effective.

The overall aim of this thesis was to increase understanding as to why NRT does not appear to be effective during pregnancy. The thesis consists of three studies.

The first study involved analysing data on 33 pregnant participants from the NRT arm of a randomised control trial who had stopped smoking and were still using 15mg/16hr nicotine patches 1 month after quitting. Salivary cotinine levels when smoking at baseline were compared with levels on NRT at 1 month. Cotinine levels were lower than those achieved from smoking (median 98.5ng/ml while smoking and 62.8ng/ml while using NRT and remaining abstinent, p = 0.045).

The second study involved 101 pregnant smokers, who were asked to provide saliva samples to measure NMR at 8-14 weeks, 18-22 weeks , 32-36 weeks gestation, 4 weeks postpartum and 12 weeks postpartum . Compared with NMR at 12 weeks postpartum, NMR was significantly higher at 18-22 weeks (26% higher, 95% CI 12% to 38%) and 32-36 weeks (23% higher, 95% CI 9% to 35%). There was no difference between the 8-14 weeks gestation or 4 weeks postpartum NMR and 12 weeks postpartum.

The third study was a qualitative study that involved semi-structured telephone interviews with 14 pregnant smokers who had recently been prescribed NRT, but self-reported low NRT adherence or discontinuing treatment prematurely. Thematic analysis was used to analyse data. Most smoked regularly while using NRT and many used NRT to cut down their cigarette intake rather than to quit abruptly. Some were concerned that using NRT instead of smoking could actually increase their nicotine dependency or cause greater harm to the fetus, and consequently often underutilised NRT.

This thesis supports the hypothesis that NRT at standard doses may be ineffective in pregnancy due to increased metabolism. The effectiveness of NRT may be hindered by the way in which NRT is used in pregnancy.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Cooper, S.
Coleman, T.J.
Lewis, S.
Keywords: Nicotine replacement therapy, Nicotine dosage, Smoking prevention in pregnancy
Subjects: W Medicine and related subjects (NLM Classification) > WM Psychiatry
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Medicine
Item ID: 32138
Depositing User: Bowker, Katharine
Date Deposited: 19 Jul 2016 06:40
Last Modified: 13 Oct 2017 17:45

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