Stillbirth among women prescribed nicotine replacement therapy in pregnancy: analysis of a large UK pregnancy cohort

Dhalwani, Nafeesa N.; Szatkowski, Lisa; Coleman, Tim; Fiaschi, Linda; Tata, Laila J.

Abstract

Objective: To compare risk of stillbirth between maternal smokers and those prescribed NRT during pregnancy.

Design: Cross-sectional analysis nested in a pregnancy cohort with longitudinal routinely-recorded medical data.

Setting: United Kingdom primary care; The Health Improvement Network (THIN) general practice database

Population: 220,630 singleton pregnancies ending in live or stillbirth, 2001-2012

Methods: Women were categorised into three groups: NRT (prescribed during pregnancy or one month before conception); smokers; controls (non-smokers without a pregnancy NRT prescription).

Main Outcome Measure: odds ratios (OR) adjusted to maternal characteristics and 95% confidence intervals (CIs) for stillbirth

Results: A total of 805 pregnancies ended in stillbirth (3.6/1,000 births). Absolute risks of stillbirth in NRT and smoker groups were both 5/1,000 births compared with 3.5/1,000 births in the control group. Compared with the control group, the adjusted odds of stillbirth in the NRT group was not statistically significant (OR=1.35, 95% CI 0.91-2.00), although it was similar in magnitude to that in the smokers group (OR=1.41, 95% CI 1.13-1.77).


Conclusions: We found no evidence of a statistically significant association between being prescribed NRT during pregnancy and odds of stillbirth compared with non-smoking women. Although our study had much larger numbers than any previously, an even larger study with biochemically-validated smoking outcome data and close monitoring of NRT use throughout pregnancy is required to exclude effects on findings of potential exposure misclassification.

Citation

Dhalwani, N. N., Szatkowski, L., Coleman, T., Fiaschi, L., & Tata, L. J. (2019). Stillbirth among women prescribed nicotine replacement therapy in pregnancy: analysis of a large UK pregnancy cohort. Nicotine and Tobacco Research, 21(4), 409–415. https://doi.org/10.1093/ntr/nty019

• Journal Article Type: Article
• Acceptance Date: Dec 26, 2017
• Online Publication Date: Jan 31, 2018
• Publication Date: Apr 1, 2019
• Deposit Date: Jan 18, 2018
• Publicly Available Date: Jan 31, 2018
• Journal: Nicotine and Tobacco Research
• Print ISSN: 1462-2203
• Electronic ISSN: 1469-994X
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 21
• Issue: 4
• Pages: 409–415
• DOI: https://doi.org/10.1093/ntr/nty019
• Keywords: Stillbirth; Nicotine replacement therapy; Smoking; Pregnancy; Maternal smoking
• Public URL: https://nottingham-repository.worktribe.com/output/907679
• Publisher URL: https://academic.oup.com/ntr/article/21/4/409/4831224
• Contract Date: Jan 18, 2018