Exposure to second-hand smoke during pregnancy

Similar to smoking during pregnancy, being exposed to second-hand smoke while pregnant results in serious risks for both the woman and the fetus. Read more about second-hand smoke...


Nicotine, carcinogens and toxic chemicals found in tobacco smoke are inhaled when people breathe in second-hand smoke.Footnote1

A pregnant woman's exposure to second-hand smoke affects many aspects of fetal development, from conception to birth. It also increases the risk of having a low birth weight baby and premature delivery.Footnote2 There is no safe level of exposure to second-hand smoke.Footnote2

Infants whose mothers smoked during pregnancy and those exposed to second-hand smoke after birth are at an increased risk for sudden infant death syndrome.Footnote2,Footnote3

Research has shown that, in 2002, exposure to second-hand smoke alone caused 92 deaths in infants under the age of one. More than 60% of these deaths were due to low birth weight and premature delivery.Footnote4

This health warning message addresses smoking and second-hand smoke during pregnancy for cigarettes and little cigars:

Pregnant woman pushing away a hand holding a cigarette

What is second-hand smoke?

Second-hand smoke, also called passive, involuntary or environmental tobacco smoke, is the combination of smoke coming directly from a burning tobacco product and the smoke exhaled by a smoker.

Many of the chemicals in tobacco smokeFootnote5,Footnote6 are present in SHS.

Cotinine, a chemical produced when nicotine degrades in the body, can be detected in body fluids and is a good indicator of exposure to second-hand smoke.Footnote2 A recent Canadian study found that 14% of non-smokers aged 6 to 79 had measurable amounts of cotinine in their urine - indicating that they had been exposed to second-hand smoke in the previous few days.Footnote7

How does second-hand smoke increase the risk of health problems?

Many chemicals in second-hand smoke can be passed on from the pregnant woman to the fetus through the placenta.Footnote2,Footnote8

Nicotine in the blood of a pregnant woman exposed to second-hand smoke can decrease the blood flow to the unborn baby. This can affect the unborn baby's heart, lungs, digestive system and central nervous system. Carbon monoxide in smoke can affect the baby's growth and may lead to low birth weight.Footnote9

How can I reduce the risk to my baby from second-hand smoke?

Cleaning or filtering the air, increased ventilation or segregated areas (non-smoking sections) cannot completely eliminate exposure to second-hand smoke nor the health risks associated with this exposure.Footnote2 The only solution to protect non-smokers is to eliminate smoking in all enclosed spaces such as restaurants, homes, and automobiles.

For women who smoke, quitting smoking before conception or early in pregnancy will produce the greatest benefits to the fetus and expectant mother. However, quitting at any point during pregnancy also provides health benefits.Footnote10

Need help to quit? Call the pan-Canadian quitline toll-free at 1-866-366-3667.

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