Smoking and pregnancy

Stopping smoking is the single most important thing you can do to protect your health. If you’re pregnant, or even thinking about getting pregnant, giving up will help protect your baby’s health too.

  • When you smoke, you breathe in nicotine, tar and carbon monoxide.
  • You also breathe in around 7,000 other chemicals, many of them poisonous – like arsenic, ammonia and benzene.
  • The tar and some chemicals build up inside your lungs, where they may eventually cause cancer.
  • Nicotine, carbon monoxide and the other chemicals rush from your lungs into your bloodstream, reducing the amount of oxygen in your blood.

All these substances get into your baby’s bloodstream from yours.

You probably already know that quitting smoking will reduce your risk of serious illnesses, but there are extra benefits if you’re pregnant.

Medical research has shown that women who smoke while pregnant:

  • are more likely to suffer from sickness, bleeding or miscarriage, and other pregnancy complications; and
  • have babies that are premature, ill or underweight and at greater risk of stillbirth or cot death.

Isn’t it too late if I’m already pregnant? Giving up smoking at any stage in your pregnancy is good for you and your baby – it’s never too late. As soon as you stop, the chemicals will start to clear from your body and your baby will get more oxygen. So give yourself and your baby a head start by giving up for good.

Read more about The effects of smoking on your baby

Get answers to some Frequently asked question on smoking and pregnancy

The effects of smoking on your baby

When you smoke a cigarette, all the poisonous substances you breathe in get into your bloodstream, and from there into your baby’s blood too. This means both of you are at risk. All the following effects have been proven by recent medical research.

Pregnancy complications

Smoking increases the risk of a number of pregnancy complications. Compared to non-smokers, smokers are:

  • between 30% and 50% more likely to have a miscarriage; and
  • twice as likely as non-smokers to develop a problem with the placenta.

Research also suggests that 1 in 10 stillbirths is caused by smoking.

Low birth weight

Smoking cuts down the amount of oxygen and nutrients that get to your baby through the placenta. Your baby needs these to grow and develop, so babies of women who smoke tend to be smaller than 6 Statistics are based on Pregnancy, Infants and Smoking - An Irish National Status Report. (2000) Department of Public Health, ERHA they should be.

If you smoke all through your pregnancy, on average your baby will be almost half a pound (200g) lighter than if you’d been a non-smoker. It may not sound like much, but size is critical. Smaller babies are more at risk of infections and other health problems. Don’t think that a smaller baby means an easier delivery. The baby’s head won’t be much smaller, and that’s the most difficult part to get out.

Cot death

If you smoke during pregnancy or after the baby is born, cot death is up to three times more likely. Some studies suggest that a quarter of all cot deaths are caused by smoking.

Asthma, wheezing, and chest infections

Smoking while pregnant damages the development of the baby’s lungs. Babies born to women who smoke are twice as likely to develop asthma and are also more likely to have other lung problems, such as wheezing and chest infections.

After your baby is born

Babies and children need to be protected from passive smoking, ideally by making your home a smoke-free zone. Cigarette smoke can trigger asthma attacks or chest infections, but there are other dangers too.

Ear infections

Babies exposed to cigarette smoke are more likely to get middle ear infections and ‘glue ear’, which can cause partial deafness.


Babies whose mothers smoke are twice as likely to suffer from infantile colic (although breastfeeding provides some protection against this).


If you smoke, your baby is up to three and a half times more likely to get meningitis. Many people carry meningitis bacteria for years in their nose and throat without ever getting ill. Cigarette smoke damages the lining of the baby’s nose and throat, allowing more bacteria to stick there, so making infection more likely.

Q: Don’t some mothers smoke during pregnancy and have healthy babies?

A: They are the lucky ones! If a woman smokes during pregnancy she takes a big chance with her baby’s health. The baby may be born prematurely, before their lungs are ready, so they may have trouble breathing.

Q: Babies often weigh less when the mother smokes. Isn’t it easier to deliver a small baby?

A: A low birth weight baby is often sick and may have health problems. Smaller babies are more likely to need special care and stay longer in the hospital. Don’t think that a smaller baby means an easier delivery. The baby’s head won’t be much smaller, and that’s the most difficult part to get out.

Q: Does cigarette smoke pass to the unborn baby?

A: Yes. When you smoke, so does the baby. When you smoke, you inhale poisons such as nicotine and carbon monoxide (the same gas that comes out of a car’s exhaust pipe). These poisons get into the placenta, which is the tissue that connects the mother and the baby. These poisons keep your unborn baby from getting the nutrients and oxygen needed to grow.

Q: Will I put on extra weight if I quit smoking when I’m pregnant?

A: You need to gain weight during pregnancy. Your baby depends on you to eat the right foods. So if you stay away from junk food and sweets, your weight gain will be fine. And you need to exercise. Your midwife or doctor can help you plan how to keep active – a brisk walk is good for most women. Even if you gain a few extra pounds, you can lose it after the baby’s born. Breastfeeding will help you lose any weight even quicker.

Q: How about if I cut down on cigarettes rather than quit for good?

A: The only way to really protect your unborn baby is to give up. Cutting down or switching to low tar cigarettes is of no benefit.

Q: Does it matter when I quit smoking?

A: The best time to give up is when you are planning a pregnancy.  If give up then, your baby will probably weigh the same as the baby of a woman who has never smoked. If you give up in the first three or four months of your pregnancy you can lower your baby’s chance of being born prematurely and with associated health problems.

Even if you give up at the end of your pregnancy, you can help your baby get more oxygen. It’s never too late, but the earlier the better for both of you!

Q: What about other people smoking around me?

A: If your partner smokes near you during your pregnancy you have a greater chance of having a low birth weight baby with the associated health problems.

Q: Does quitting smoking benefit me as well as the baby?

A: Pregnancy is a great time for you to give up. No matter how long you’ve been smoking, your body will benefit. You will feel better and have more energy to go through the pregnancy and to care for your new baby.

Of course, you will also avoid many of the future health risks of smoking such as heart disease, cancer and other lung problems. AND you will save money that you can spend on yourself and your new baby.

Q: If I quit smoking during pregnancy, will I have a hard time handling the stress?

A: You can learn to relax in other ways that are much better for you and your unborn baby. When you feel tense, you can take some deep breaths or chew sugarless gum. You can also do something with your hands like sew something for the baby or call a friend.

These are safer ways to handle stress. You can also remind yourself that smoking will not make things any better.

Q: If I breastfeed my baby, does the nicotine get into the milk?

A: Breastfeeding is the best way to feed a new baby.  A small amount of the chemicals in cigarette smoke pass to the baby via the breastmilk.  The safest option for breastfeeding mothers is not to smoke at all, but if you are unable to give up, smoke just after a breastfeed rather than before.

Q: Are there any long-term harmful effects on the baby if I smoke during pregnancy?

A: Yes, there can be. Smoking during pregnancy may mean that after your child is born they will have more colds and other lung problems, such as asthma.

Your child may also be a slower learner in school. They may be smaller than children of non-smokers, and they are more likely to smoke when they get older because they see their parents smoking.

Q: I know I shouldn’t smoke during pregnancy, but is it alright to go back to smoking after the baby is born?

A: It makes no sense at all for you to go back to smoking!  Even after the baby is born, your smoking can hurt the baby.

Babies have very small lungs and airways which get even smaller when they breathe smoke-filled air. Smoking can make it hard for the baby to breathe. It can cause lung problems like bronchitis and pneumonia.

Babies of mothers who smoke also get more colds and coughs and middle-ear infections. You should also ask family, friends, babysitters and childcare workers to smoke outdoors.