The risks of secondhand smoke

Secondhand smoke is invisible and colourless. But you may still be breathing in chemicals that can harm you and your unborn baby.

What are the risks of secondhand smoke?

Secondhand smoke (also known as passive smoking) can affect you and your baby before and after their birth.

Breathing in other people’s tobacco smoke while pregnant causes toxins (nicotine and carbon monoxide) to enter your blood and pass into your unborn baby.

Secondhand smoke can increase the risk of:

If you smoke, it may make it harder for you to quit if people around you smoke.  

Is secondhand smoke from vaping safe? 

An e-cigarette is an electronic device that lets you breathe in nicotine in a vapour, rather than smoke (this is why it is sometimes known as vaping).  

There has not been much research into the safety of e-cigarettes in pregnancy. We know that e-cigarettes do not produce tar or carbon monoxide, the 2 main toxins in cigarette smoke. Carbon monoxide is particularly harmful to developing babies.

The vapour from an e-cigarette contains some of the potentially harmful chemicals found in cigarette smoke, but at much lower levels. This means that if someone nearby is vaping, you may breathe in some of these chemicals. We don’t yet know if this is harmful.

Until we know more, the safest way to protect your baby is to avoid both secondhand tobacco smoke and secondhand vapour from e-cigarettes. Don’t be afraid to ask people not to vape around you, to help keep your unborn child safe.

How do I know if I’m affected by secondhand smoke?

Your midwife should do a carbon monoxide breath test at your first antenatal appointment (also known as the booking appointment). This will measure the levels of carbon monoxide gas in your body. Carbon monoxide is a poisonous gas found in cigarette smoke, including secondhand smoke.

What can I do about secondhand smoke?

It doesn’t matter how much people try to keep their smoke away from you. If someone smokes in your home, you and your baby could still be exposed. Opening windows and doors or smoking in another room will not make it safe. Smoke can linger in the air for 2 to 3 hours after someone finishes a cigarette, even with a window open.

The smoker in your home may not be aware of how their smoking affects you and your baby. Talk to them about quitting smoking for you and your baby’s sake, if not theirs. There is support available, if they need it. Your midwife can talk to you both about this.

If the smoker can’t or won’t quit, make sure they don’t smoke in the house or car.  

You could also try:

  • avoiding places where people will be smoking indoors
  • asking drivers not to smoke in the car or avoid travelling with them
  • telling visitors to smoke outside, with the door and any nearby windows closed  
  • keeping an umbrella, raincoat and outdoor shoes by the door, so that it’s easy for people to smoke outside even if it's raining
  • showing people this information
  • asking your pharmacist, midwife or GP for advice on how to keep you and your baby safe from other people's smoke
  • ask any smokers you live with to contact NHS stop smoking services.

Secondhand smoke after your baby is born

It is important to stay smoke free after your baby is born. Secondhand smoke is especially harmful for babies and children because they have less well-developed airways, lungs and immune systems.

Not smoking around your baby will reduce the risk of:

  • asthma
  • chest infections – like pneumonia and bronchitis
  • meningitis
  • Ear infections
  • coughs and colds.

Find out more about smoking after your baby is born

NHS. Stop smoking in pregnancy. (Page last reviewed: 10 January 2023 Next review due: 10 January 2026)

Royal College of Obstetricians & Gynaecologists Smoking and pregnancy.

NHS. Passive Smoking. (Page last reviewed: 5 May 2022 Next review due: 5 May 2025)

NHS. Quit Smoking. (Page last reviewed: 5 May 2022. Next review due: 5 May 2025)

Review dates
Reviewed: 23 November 2023
Next review: 23 November 2026