4.16 Secondhand smoke and pregnancy

Last updated: January 2017
Suggested citation: Campbell MA, Ford C, & Winstanley MH. Ch 4. The health effects of secondhand smoke. 4.16 Secondhand smoke and pregnancy. In Scollo, MM and Winstanley, MH [editors]. Tobacco in Australia: Facts and issues. Melbourne: Cancer Council Victoria; 2017. Available from http://www.tobaccoinaustralia.org.au/chapter-4-secondhand/4-16-secondhand-smoke-and-pregnancy

Determining the health impacts of secondhand smoke exposure during pregnancy is challenging because it is difficult to differentiate between the impacts of maternal secondhand smoke exposure, potential damage to sperm from paternal active smoking, and the influence of past maternal active smoking. This is particularly the case for rare conditions such as birth defects or childhood cancers.

Biomarkers to determine neonatal exposure to tobacco smoke prior to birth can be measured in cord blood, or neonatal urine, hair, nails, amniotic fluid and meconium (the first faecal matter passed by the baby after birth). When this is studied these samples are usually collected at or soon after birth. Metabolites of nicotine, in particular cotinine, in cord blood and meconium is most commonly used to detect exposure to secondhand smoke in fetuses of non-smoking mothers. Biomarkers in cord blood indicate exposure to tobacco smoke in the few days before delivery, whereas biomarkers in meconium accumulate over several months of gestation.1

4.16.1 Fertility

Some evidence suggests that exposure to secondhand smoke may be associated with reduced fertility or fecundity (rate of conception) in women, however these effects may be difficult to separate from the effects of active smoking on the partner’s fertility.2-4 More research is required before these outcomes may be stated with certainty.3 In women undergoing IVF treatment, exposure to secondhand smoke may lead to a reduced chance of successful implantation,5, 6 although further research is needed.

4.16.2 Low birthweight and preterm delivery

Maternal secondhand smoke exposure is associated with preterm birth7, 8 and low birth weight.9-11 Estimates of the mean decrease in weight calculated by various reviews range from around 30 g to 60 g, and secondhand smoke exposure has been demonstrated to increase the risk of low birthweight <3500g by up to 22%.2, 3, 9, 12 One study examining women exposed to secondhand smoke who carried specific genotypes related to metabolising enzymes found that these women delivered babies with mean birthweight decrements of around 160 g and 200 g.3 This suggests there may be a sub-group of women whose fetuses are more susceptible to the effects of maternal secondhand smoke exposure.2

Mechanisms for lower birthweight in babies of non-smoking mothers exposed to secondhand smoke are likely to be similar to those that cause lower birthweight in infants of active smokers. Factors contributing to low birthweight may include preterm delivery, intrauterine growth retardation, or a combination of the two.9 Major reviews differ in their conclusions on the relationship of secondhand smoke exposure and preterm delivery. The California Environmental Protection Agency report (2005) concluded that secondhand smoke is a cause of preterm delivery, and may cause intrauterine growth retardation.2 The US Surgeon General’s report (2006) concluded that the evidence for preterm delivery is mixed but ‘suggestive’ of causality.9 This report also cited research suggesting that lower birthweight may be the result of reduced oxygen to the fetus.9 Some studies have found that secondhand smoke exposure of the pregnant mother increases the risk for maternal inflammation, reduced placental weight and fetal growth restriction.13-16

4.16.3 Lung development in the unborn child

There is clear evidence that smoking by a pregnant mother impairs fetal lung development.3, 9, 17 Animal studies suggest that maternal exposure to secondhand smoke also causes changes in fetal lung structure,9, 17 including direct effects on alveolar development in fetal lungs.18 One study on pregnant sheep indicated that maternal exposure to secondhand smoke may decrease blood flow and increase vascular resistance in the fetal lungs. In this study secondhand smoke also appeared to reduce the normal dilation of blood vessels in the fetal lungs in response to increased oxygen. These effects are associated with a marked decrease in oxygen within the fetus, and may affect lung circulation at birth.19

4.16.4 Spontaneous abortion (miscarriage) and stillbirth

Findings on an association between maternal exposure to secondhand smoke and an increased rate of spontaneous abortion are mixed, and further research is needed.2, 3, 9, 20 A meta-analysis based on 19 studies demonstrated that maternal secondhand smoke exposure was associated with an increased risk of stillbirth.20

4.16.5 Birth defects

A 2011 meta-analysis showed that maternal secondhand smoke exposure was associated with an increased risk of birth defects, although it did not have the power to determine the risk of specific congenital abnormalities.20 A systematic review of secondhand smoke exposure and congenital malformations found maternal secondhand smoke exposure was associated with a 1.5-fold increase in the risk of orofacial clefts, similar to the increased risk demonstrated for active smoking.21 Further research is needed to determine if this relationship is causal and due to exposure of the mother to secondhand smoke or the effects of tobacco smoke on sperm.3

4.16.6 Cardiovascular effects

One study of fetal autopsies suggested that women exposed to secondhand smoke were more likely to have lesions in the walls of the fetal artery and adjoining vessels, which reflect the initial stages of atherosclerosis (narrowing of the arteries by fatty deposits).22

References

1. Llaquet H, Pichini S, Joya X, Papaseit E, Vall O, et al. Biological matrices for the evaluation of exposure to environmental tobacco smoke during prenatal life and childhood. Analytical and Bioanalytical Chemistry, 2009; 396(1):379–99. Available from: http://www.springerlink.com/content/4960m70q40652246/fulltext.html

2. Office of Environmental Health Hazard Assessment and California Air Resources Board. Health effects of exposure to environmental tobacco smoke: Final report, approved at the Panel's June 24, 2005 meeting. Sacramento: California Environmental Protection Agency, 2005. Available from: http://www.oehha.ca.gov/air/environmental_tobacco/2005etsfinal.html

3. US Department of Health and Human Services. How tobacco smoke causes disease: The biology and behavioral basis for smoking-attributable disease. A report of the Surgeon General, Atlanta, Georgia: US 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. Available from: http://www.surgeongeneral.gov/library/tobaccosmoke/report/index.html

4. Peppone LJ, Piazza KM, Mahoney MC, Morrow GR, Mustian KM, et al. Associations between adult and childhood secondhand smoke exposures and fecundity and fetal loss among women who visited a cancer hospital. Tobacco Control, 2009; 18(2):115–20. Available from: http://tobaccocontrol.bmj.com/cgi/content/abstract/18/2/115

5. Neal M, Hughes E, Holloway A, and Foster W. Sidestream smoking is equally as damaging as mainstream smoking on IVF outcomes.2005. Human Reproduction, 2005; 20(9):2531–5. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15919779

6. Kazemi A, Ramezanzadeh F, Esfahani MH, Saboor-Yaraghi AA, Nejat S, et al. Impact of environmental tobacco smoke exposure in women on oxidative stress in the antral follicle and assisted reproduction outcomes. Journal of Research in Medical Sciences, 2013; 18(8):688–94. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24379845

7. Cui H, Gong TT, Liu CX, and Wu QJ. Associations between passive maternal smoking during pregnancy and preterm birth: Evidence from a meta-analysis of observational studies. PLoS One, 2016; 11(1):e0147848. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26808045

8. Ion RC, Wills AK, and Bernal AL. Environmental tobacco smoke exposure in pregnancy is associated with earlier delivery and reduced birth weight. Reproductive Sciences, 2015; 22(12):1603–11. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26507870

9. US Department of Health and Human Services. The health consequences of involuntary exposure to tobacco smoke: A report of the surgeon general. Atlanta, Georgia: US Department of Health and Human Services, Centers for Disease Control and Prevention, Coordinating Center for Health Promotion, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2006. Available from: http://www.cdc.gov/tobacco/data_statistics/sgr/sgr_2006/index.htm

10. Wahabi HA, Mandil AA, Alzeidan RA, Bahnassy AA, and Fayed AA. The independent effects of second hand smoke exposure and maternal body mass index on the anthropometric measurements of the newborn. BMC Public Health, 2013; 13:1058. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24209496

11. Crane J, Keough M, Murphy P, Burrage L, and Hutchens D. Effects of environmental tobacco smoke on perinatal outcomes: A retrospective cohort study. British Journal of Obstetrics and Gynacology, 2011; 118:865–71. Available from: http://onlinelibrary.wiley.com/doi/10.1111/j.1471-0528.2011.02941.x/full

12. Salmasi G, Grady R, Jones J, and McDonald S. Environmental tobacco smoke exposure and perinatal outcomes: A systematic review and meta-analyses. Acta Obstetricia et Gynecologica Scandinavica, 2010; 89(4):423–41. Available from: http://informahealthcare.com/doi/full/10.3109/00016340903505748

13. Reeves S and Bernstein I. Effects of maternal tobacco-smoke exposure on fetal growth and neonatal size. Expert Reviews in Obstetrics and Gynecology, 2008; 3(6):719–30. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19881889

14. Niu Z, Xie C, Wen X, Tian F, Ding P, et al. Placenta mediates the association between maternal second-hand smoke exposure during pregnancy and small for gestational age. Placenta, 2015; 36(8):876–80. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26051507

15. Niu Z, Xie C, Wen X, Tian F, Yuan S, et al. Potential pathways by which maternal second-hand smoke exposure during pregnancy causes full-term low birth weight. Scientific Reports, 2016; 6:24987. Available from: http://www.ncbi.nlm.nih.gov/pubmed/27126191

16. Varvarigou A, Fouzas S, and Beratis N. Effect of prenatal tobacco smoke exposure on fetal growth potential. Journal of Perinatal Medicine, 2010; 38(6):683–7. Available from: http://www.reference-global.com/doi/pdf/10.1515/JPM.2010.101

17. Joad JP. Smoking and pediatric respiratory health. Clinics in Chest Medicine, 2000; 21(1):37–46. Available from: http://www.ncbi.nlm.nih.gov/pubmed/10763088

18. Zhong C, Zhou Y, Joad J, and Pinkerton K. Environmental tobacco smoke suppresses nuclear factor-{kappa}b signaling to increase apoptosis in infant monkey lungs. American Journal of Critical Care Medicine, 2006; 174(4):428–36. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16709937

19. Houfflin-Debarge V, Sabbah-Briffaut E, Aubry E, Deruelle P, Alexandre C, et al. Effects of environmental tobacco smoke on the pulmonary circulation in the ovine fetus. American Journal of Obstetrics and Gynecology, 2011; 204(5):450 e8–14. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21333966

20. Leonardi-Bee J, Britton J, and Venn A. Secondhand smoke and adverse fetal outcomes in nonsmoking pregnant women: A meta-analysis. Pediatrics, 2011; 127(4):734–41. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21382949

21. Sabbagh HJ, Hassan MH, Innes NP, Elkodary HM, Little J, et al. Passive smoking in the etiology of non-syndromic orofacial clefts: A systematic review and meta-analysis. PLoS One, 2015; 10(3):e0116963. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25760440

22. Mecchia D, Lavezzi AM, Mauri M, and Matturri L. Feto-placental atherosclerotic lesions in intrauterine fetal demise: Role of parental cigarette smoking. Open Cardiovascular Medicine Journal, 2009; June 11(3):51–6. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19572018

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