Exposure to second-hand smoke during pregnancy

Exposure to second-hand smoke during pregnancy poses serious risks for mother and baby.

Key facts about second-hand smoke exposure during pregnancy

  • People who do not smoke but who are exposed to second-hand smoke during pregnancy are more likely to experience a stillbirth and more likely to have a baby with a birth defect.End Note 1
  • Second-hand smoke exposure during pregnancy increases the risk of reduced fetal growth or having a baby with low birth weight.End Note 2
  • Reduced fetal growth and low birth weight can result in complications for the baby leading to disease or death.End Note 3End Note 4

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What is second-hand smoke?

Second-hand smoke is the smoke that comes from a burning tobacco product and the smoke exhaled by a person who is smoking. Many of the chemicals in tobacco smoke are therefore also found in second-hand smoke.

In Canada, an estimated 22% of those who do not smoke are exposed to second-hand smoke every day or almost every day.End Note 5End Note 6 Children and adolescents have the highest measurable exposure to second-hand smoke among those exposed in the home.End Note 5End Note 6

How does second-hand smoke increase the health risks to my baby and me?

There is no safe level of exposure to second-hand smoke. Even brief exposure can be harmful to health.End Note 2End Note 8End Note 9 Nicotine, cancer-causing chemicals, and toxic chemicals found in tobacco smoke enter the body when someone breathes in second-hand smoke.End Note 7End Note 9 During pregnancy, many chemicals found in second-hand smoke can pass to the baby through the placenta.End Note 10

Nicotine in the bloodstream during pregnancy can affect the function of the placenta and decrease blood flow to the developing baby.End Note 9 This negative outcome can affect the developing baby's heart, lungs, digestive system, and central nervous system.End Note 11 Carbon monoxide, a toxic substance in cigarette smoke, can slow the baby's growth and lead to low birth weight.End Note 9

How can I lower the health risks to my baby and me?

Cleaning or filtering the indoor air, increasing ventilation, or segregating smoking areas do not eliminate exposure to second-hand smoke nor its associated health risks.End Note 2 The only solution to avoid exposure to second-hand smoke and its associated health risks is to eliminate smoking in all enclosed spaces such as vehicles and homes.

Preventing exposure to tobacco smoke, before and after birth, reduces the risk to babies. Preventive measures includes avoiding smoking and exposure to second-hand smoke during and after pregnancy, and keeping the baby away from tobacco smoke in the home, vehicle, and anywhere else the baby spends time.

Health benefits of quitting tobacco use at any age

Quitting tobacco use reduces the risk of premature death, improves health, and enhances quality of life.End Note 12 Quitting at any age is beneficial to one's health.End Note 12 Even people who have smoked or used tobacco heavily for many years benefit from it.End Note 12End Note 13 Quitting is the most important thing someone who smokes can do to improve their health.

Read more about the benefits of quitting smoking.

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End Notes

End Note 1

Leonardi-Bee J, Britton J, Venn A. Secondhand smoke and adverse fetal outcomes in nonsmoking pregnant women: A meta-analysis. Pediatrics. 2011;127(4): 734-741. doi: https://doi.org/10.1542/peds.2010-3041.

Return to footnote 1 referrer

End Note 2

U.S. Department of Health and Human Services. The Health Consequences of Involuntary Exposure to Tobacco Smoke. A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centres for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking an Health; 2006.

Return to footnote 2 referrer

End Note 3

Breeze A, Lees C. Prediction and perinatal outcomes of fetal growth restriction. Seminars in Fetal & Neonatal Medicine. 2007;12:383-397. doi:10.1016/j.siny.2007.07.002.

Return to footnote 3 referrer

End Note 4

Malin G, Morris R, Riley R, Teune M, Khan K. When is birthweight at term abnormally low? A systematic review and meta-analysis of the association and predictive ability of current birth weight standards for neonatal outcomes. BJOG. 2014;121:515-526. doi: 10.1111/1471-0528.12517.

Return to footnote 4 referrer

End Note 5

Wong SL, Malaison E, Hammond D, Leatherdale ST. Secondhand smoke exposure among Canadians: cotinine and self-report measures from the Canadian Health Measures Survey 2007–2009. Nicotine & Tobacco Research. 2013;15(3): 693–700. https://doi.org/10.1093/ntr/nts195.

Return to footnote 5 referrer

End Note 6

Levesque J, Mischki T. Exposure to tobacco smoke among Canadian nonsmokers based on questionnaire and biomonitoring data. Health Reports. 2021. doi: https://www.doi.org/10.25318/82-003-x202100200002-eng.

Return to footnote 6 referrer

End Note 7

International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans: Tobacco Smoke and Involuntary Smoking. Vol. 83. Lyon (France): International Agency for Research on Cancer, 2004.

Return to footnote 7 referrer

End Note 8

U.S. Department of Health and Human Services. The Health Consequences of Smoking—50 Years of Progress: A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2014.

Return to footnote 8 referrer

End Note 9

U.S. Department of Health and Human Services. A Report of the Surgeon General: How Tobacco Smoke Causes Disease The Biology and Behavioral Basis for Smoking-Attributable Disease. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health; 2010.

Return to footnote 9 referrer

End Note 10

Lee M, Ha M, Hong Y, Park H, Kim Y, Kim EJ, Kim Y, Ha E. Exposure to prenatal secondhand smoke and early neurodevelopment: Mothers and Children's Environmental Health (MOCEH) study. Environmental Health. 2019;18(1): 22. doi: 10.1186/s12940-019-0463-9.

Return to footnote 10 referrer

End Note 11

Fajersztajn L, Veras MM. Hypoxia: From placental development to fetal programming. Birth Defects Research. 2017;109(17):1377-1385. doi: 10.1002/bdr2.1142.

Return to footnote 11 referrer

End Note 12

U.S. Department of Health and Human Services. Smoking Cessation: A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2020.

Return to footnote 12 referrer

End Note 13

U.S. Department of Health and Human Services. The Health Consequences of Smoking. A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health; 2004.

Return to footnote 13 referrer

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