Home Am I at Risk? Secondhand Smoke & Pregnancy

Secondhand Smoke & Pregnancy

Does secondhand smoke increase my risk for heart disease?

Yes. Studies from the mid-1980s and later show that secondhand smoke increases the risk of heart disease by 25% to 30% in men and women who do not smoke. Earlier research did not show such a dramatic effect mainly because they were done before laws were passed to cut industrial pollution or smoking in the workplace. This meant it was likely that the control group was also exposed to smoke at work or outdoors. On top of that, one analysis found that the studies showing that secondhand smoke was harmless tended to be written by people with ties to the tobacco industry. Secondhand smoke includes:

  • Sidestream smoke – the smoke that comes from the tip of a burning cigarette
  • Mainstream smoke – the smoke that is inhaled and then exhaled by smokers

Unlike the case with lung cancer, the risk of heart attack and heart disease rises rapidly at low doses of tobacco smoke. After 20 minutes’ exposure to secondhand smoke, the blood of nonsmokers thickens, making it more likely to clot (and potentially trigger a heart attack). Sidestream smoke has a stronger blood thickening effect than mainstream smoke. After 15 to 30 minutes’ exposure, the arteries are stiffer. Spending 2 hours in a smoking room increases the risk of heart rhythm problems.

Do smoke-free policies reduce heart disease?

Smoke-free policies such as a ban on smoking in the workplace have helped reduce nonsmokers’ exposure to tobacco smoke. Scientists can confirm this by measuring blood levels of cotinine, a breakdown product of nicotine (nicotine doesn’t stay in the blood long enough to be recorded over time).There was a 75% reduction in blood levels of cotinine in nonsmokers from 1999-2002 compared with 1988-1991. It is too early to tell whether this will translate into a dramatic reduction in the risk of heart disease and heart attack. One interesting study comes from the small town of Helena, Montana, where a law banning smoking in public places was passed and then challenged and reversed. When the ban was in place, the number of people hospitalized for heart attack fell to 24 from an average of 40 in the same month the years before the law was in place. Once the law was reversed, the number of heart attacks rose again.

Does smoking during pregnancy harm the baby?

Yes. It is very important to quit smoking if you are pregnant. Smoking impairs the baby’s growth and development. Women who smoke during pregnancy have a higher risk of going into labor early or having a low-weight baby.

Can I use medications to help me quit if I’m pregnant?

If you are pregnant, you should not use nicotine replacements or Zyban unless your healthcare provider has told you to. There is not a lot of safety information on the use of these medications during pregnancy.

What if I quit smoking during my pregnancy but start up again after the baby is born?

Up to 85% of women who quit smoking at some stage during pregnancy continue to smoke after the baby is born. Many women are motivated to quit for the health of their unborn baby, but a mother’s smoking also poses risks for the baby after he or she is born. Babies born to mothers who smoke heavily are more likely to be hospitalized in their first 8 months (for respiratory or stomach problems) than babies born to nonsmoking moms. Having a smoking mother increases a baby’s risk of sudden infant death syndrome (SIDS, or crib death) 2- to 4-fold. Women often put their family’s needs first but, remember, if you neglect your own health, you may not be well enough to look after your family. Not smoking also sets an example for your children and increases the likelihood that they won’t start smoking.


  1. Chobanian AV, Bakris GL, Black HR, et al. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: The JNC 7 Report. JAMA. May 21, 2003 2003;289(19):2560-2571.


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