Smoking and pregnancy

Last updated: 03 October 2007

Smoking and your unborn baby

The umbilical cord is your baby's lifeline. The blood that flows through this cord gives your baby all the oxygen and nutrients it needs to grow.

When you smoke a cigarette you inhale the gas carbon monoxide. This means that the amount of oxygen available to your baby through the umbilical cord is reduced. This makes the baby's heart beat more rapidly, and increases overall stress on its developing body. Smoking can also reduce the flow of blood through the placenta, which limits the amount of nutrients that feed the baby.

Smoking, pregnancy and birth

• Smokers have a greater risk of ectopic pregnancy (a pregnancy outside the uterus) and miscarriage
• Smokers have a higher risk of having a premature baby.
• Smokers are more likely to have complications of pregnancy affecting the placenta.
• Smokers are more likely to have a low birthweight baby.
• Babies born with a lower than average birthweight are at more risk of infection and other health problems.
• Smoking during pregnancy increases the chances of the baby dying at or shortly after birth.

After baby is born

• The risk of Sudden Infant Death Syndrome (SIDS, or 'cot death') is increased in babies of mothers who smoke during pregnancy or after birth. Keep baby safe by asking smokers to always go outside your home and car to smoke.
• Many of the 4,000+ chemicals the mother inhales are passed on to the baby through breast milk and through passive smoking.
• Babies of smokers are more likely to suffer from asthma and other respiratory infections.
• Children exposed to tobacco smoke have more middle ear infections.

Breastfeeding

Breast milk protects your baby against infection, but if you smoke, you are likely to have reduced production of breast milk and some harmful substances may be absorbed by the baby through the breast milk. If you are having difficulty quitting smoking, try not to smoke just before or during feeds, and always go outside to smoke. If you can't give it up completely, keep working on it. Remember, even if you do smoke, breastfeeding is preferable to bottle-feeding because of the important nutrients and protective factors in breast milk.

As a mother, protect your baby's health by not smoking and by asking family and visitors to always go outside to smoke.

Passive smoking

Every time someone smokes around you or your children, you are all smoking too. This is called passive smoking or environmental tobacco smoke (ETS). ETS can affect the health of children:

• Young children have smaller, more delicate lungs than adults. This may mean that they are more affected by tobacco smoke and the chemicals it contains.
• Children of smokers are more likely to suffer from asthma and other respiratory infections.
• Children exposed to tobacco smoke are more likely to cough during the night.

The fact sheet Car and home smoke free zone has more information.

Common Questions

Can I use NRT during my pregnancy?
In pregnancy, it is preferable to try to quit first without using nicotine replacement therapy (NRT). However, NRT is less harmful than smoking during pregnancy, as the pregnant woman and the baby receive less nicotine and no exposure to carbon monoxide and other toxic substances. NRT in the forms of gum, lozenge, sublingual tablet or inhaler (rather than patch) may be considered if you are pregnant and unable to quit, but it is important to discuss using NRT with your doctor. The benefits of quitting smoking are likely to outweigh the risks from using NRT or continuing to smoke. NRT is beneficial to highly dependent smokers who are likely to have greater difficulty in quitting and who also have a greater risk of developing problems during the pregnancy and birth.

Can I use NRT while I'm breastfeeding?
Nicotine passes freely into breast milk, just as it easily crosses the placenta during pregnancy. It is preferable to avoid exposing an infant to any potentially harmful substance. However, the overall dose of nicotine obtained from using NRT is substantially lower than that obtained by smoking. When using NRT there is no contamination of breast milk with other components of tobacco smoke such as carbon monoxide and the 4,000 or more other dangerous chemicals. Self-administered nicotine replacement products that provide intermittent nicotine, such as the gum, lozenge, sublingual tablet (microtab) or inhaler are preferable to the constant delivery of nicotine as provided by the patch. The use of the NRT can then be timed to minimise the level of nicotine in the milk when breastfeeding by using it immediately after a feed to extend the time between using the NRT and the baby's next feed.

If I am already three months pregnant, should I quit?
If you quit now, your risk of having a low birthweight baby will be similar to that of a non-smoker

Is it OK to cut down, rather than quit?
There is no safe level of smoking. Even a few cigarettes a day means your baby is exposed to poisons that might affect your baby's development and growth. Reducing the number of cigarettes does not reduce the harm as sub-consciously, the way you smoke may change, such as smoking more of each cigarette.4 You are also damaging your own health at a vital time. It is never too late to quit. Quitting at any time during pregnancy is likely to reduce the harmful effects of smoking on your baby.

If I have a low birthweight baby, will the birth be quicker and easier?
Having a low birthweight baby does not make things easier for you or your baby at birth. A smaller baby is more likely to become stressed during birth. Labour with a small, under-weight baby is not easier or shorter than labour with an average sized baby. The damage from smoking that causes the baby to be small also puts the baby at risk of other health problems and labour complications.

If I stop smoking, how much weight will I put on?
Your body needs more kilojoules during pregnancy to cope with the needs of your growing baby and to maintain your own health. A weight gain of 10 to 13 kilograms is desirable. A balanced diet means eating a moderate amount of food, selected from a wide variety of sources.

If smoking relaxes me, then is this good for my baby?
Smoking might seem relaxing, but it really increases your heart rate and blood pressure. Every puff on a cigarette decreases the amount of oxygen in your bloodstream and this reduces the amount of oxygen available to your baby. This makes the baby's heart beat more rapidly, and increases overall stress on its developing body.

References

1. British Medical Association 2004, Smoking and reproductive life, the impact of smoking on sexual, reproductive and child health, British Medical Association Board of Science and Education & Tobacco Control Resource Centre, BMA Publications, London, February 2004.

2. US Department of Health and Human Services 2004, The Health and Consequences of Smoking: A Report of the Surgeon General US Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health 2004.

3. US Department of Health and Human Services 2006, The health consequences of involuntary exposure to tobacco smoke, A report of the Surgeon General, Centers for Disease Control and Prevention, Coordinating Center for Health Promotion, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health.

4. Commonwealth of Australia 2006, National clinical guidelines for the management of drug use during pregnancy, birth and the early development years of the newborn, NSW Department of Health.

Related Links

• Car and home smoke free zone  http://www.health.nsw.gov.au/factsheets/general/smokefree.html
• Getting ready to quit  http://www.health.nsw.gov.au/factsheets/general/readyquit.html