Environmental Tobacco Smoke Exposure in Pregnancy is Associated With Earlier Delivery and Reduced Birth Weight

Rachel C Ion, Andrew K Wills, Andrés López Bernal

Research output: Contribution to journalArticle (Academic Journal)peer-review

32 Citations (Scopus)
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The association between maternal smoking and preterm birth (PTB) has been known for more than 50 years but the effect of passive smoking is controversial. This retrospective cohort study in Bristol, United Kingdom, examines the effect of environmental tobacco smoke exposure (ETSE) on gestational age at delivery, birth weight, PTB, and being small-for-gestational age (SGA). Environmental tobacco smoke exposure was defined by either self-report or exhaled carbon monoxide (eCO) levels, and exposed women were compared with unexposed controls. Two models were used: The first included all women with adjustment for maternal smoking, and the second considered nonsmokers alone. Both models were further adjusted for maternal age, body mass index, parity, ethnicity, employment status, socioeconomic position, asthma, preeclampsia, and offspring sex. Logistic regression and likelihood ratio tests were used to test for any association between exposure and the binary outcomes (PTB and SGA), while linear regression and F tests were used to test for associations between exposure and the continuous outcomes. There were 13 359 deliveries in 2012 to 2014, with complete data for 5066 and 4793 women in the self-reported and eCO-measured exposure groups, respectively. Self-reported exposure was associated with earlier delivery (-0.19 weeks; 95% confidence interval [CI]: -0.32 to -0.05) and reduced birth weight (-56 g, 95% CI: -97 to -16 g) but no increase in the risk of PTB or SGA. There was no evidence for an association between eCO-measured exposure and any of the outcome measures. This information is important when advising women and their families and adds further support to continued public health efforts to reduce exposure to tobacco smoke.

Original languageEnglish
Pages (from-to)1603-11
Number of pages9
JournalReproductive sciences (Thousand Oaks, Calif.)
Issue number12
Publication statusPublished - Dec 2015


  • passive smoking
  • birth weight
  • preterm/premature birth
  • carbon monoxide
  • pregnancy outcome


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