Maternal smoking is an established risk factor for many adverse birth outcomes, including orofacial clefts, low birth weight, and prematurity1. However, the risk associated with congenital heart defects (CHDs) is less clear. Some data suggest that maternal smoking during pregnancy may increase modestly the risk of certain CHDs. However, even a modestly increased risk, if real, could translate into many occurrences of CHDs given the frequency of smoking among women of reproductive age and the large number of prenatally exposed infants, nearly half a million yearly in the United States9. Elimination of smoking is an important part of wellness and preconception care because of its many positive health effects on women and their children.
With respect to CHDs, studies have shown maternal smoking to be linked most consistently with septal defects6,7, especially atrial septal defects2-4,6. Some studies have also linked maternal smoking with a modest risk of right ventricular outflow tract obstruction (e.g. pulmonary stenosis),4,6 truncus arteriosus,3,4 levo-transposition of the great arteries,2,4 dextro-transposition of the great arteries,5 tetralogy of Fallot,2 atrioventricular septal defects,2 single ventricle,2 and patent ductus arteriosus.3 Overall, accumulating data suggest modest risks for select CHDs, that heavier smoking may be associated with higher risk, and that genetics may factor into how susceptible a developing heart is to the adverse effects maternal cigarette smoking5,6, 8. However, studies to date have been inconsistent with some reporting increased risks for many CHDs2 whereas others do not.2-5 Studies that have examined maternal smoking and CHDs include population-based studies in the United States (the Baltimore-Washington Infant Study4,5 and the National Birth Defects Prevention Study6), Sweden,3 and Lithuania.7 The mixed findings on specific defects may reflect differences in population, timing of study, or study methods.
Strategies for prevention:
Maternal smoking has been linked conclusively with an increased risk for many adverse reproductive outcomes1. One objective of the Healthy People 2020 prevention project is to increase the percentage of women who do not smoke during pregnancy to 98% through multi-component interventions and campaigns.10 Given the high frequency of maternal smoking, decreasing smoking during pregnancy could lead to significant numbers of healthier mothers, healthier pregnancies and babies, and possibly fewer infants with CHDs.
1. Centers for Disease Control and Prevention. Smoking Prevalence Among Women of Reproductive Age --- United States, 2006. MMWR Morb Mortal Wkly Rep. 2008 57(31);849-852
2. Jenkins KJ, et al. Noninherited risk factors and congenital cardiovascular defects: current knowledge: a scientific statement from the American Heart Association Council on Cardiovascular Disease in the Young: endorsed by the American Academy of Pediatrics. Circulation. 2007 Jun 12;115(23):2995-3014.
3. Källén K. Maternal smoking and congenital heart defects. Eur J Epidemiol. 1999 Sep;15(8):731-7.
4. Alverson CJ, et al. Maternal smoking and congenital heart defects in the Baltimore-Washington Infant Study. Pediatrics. 2011 Mar;127(3):e647-53
5. Ferencz C, Correa-Villasenor A, Loffredo CA, eds. Genetic and Environmental Risk Factors of Major Cardiovascular Malformations: The Baltimore-Washington Infant Study: 1981-1989. Armon, NY: Futura Publishing Co; 1997.
6. Malik S, et al, Maternal smoking and congenital heart defects. Pediatrics. 2008 Apr;121(4):e810-6.
7. Kuciene R , et al. Parental cigarette smoking and the risk of congenital heart septal defects. Medicina (Kaunas). 2010;46(9):635-41.
8. Shaw GM, Iovannisci DM, Yan W, et al. Risks of human conotruncal heart defects associated with 32 single nucleotide polymorphisms of selected cardiovascular disease-related genes. Am J Med Genet. 2005;128(1):21-26.
9. Martin JA, Hamilton BE, Sutton PD. Births: Final Data for 2006. National Vital Statistics Reports. 2009, 57(7).
10. US Department of Health and Human Services. Healthy People 2020: Understanding and Improving Health
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