Pregnancy and smoking

Smoking while pregnant exposes a woman and her unborn child to an increased risk of health problems. Australian studies indicate that approximately 17 per cent of women smoke during pregnancy, although this rate appears to be declining. Passive smoking can also affect a pregnant woman and her child.

A woman who smokes while pregnant is at increased risk of a wide range of problems including ectopic pregnancy, miscarriage and premature labour. Women who smoke are twice as likely to give birth to a low weight baby compared to non-smokers. Low birth weight babies are more vulnerable to infection, other health problems such as breathing difficulties, death and long-term health problems in adulthood.

The more cigarettes smoked during pregnancy, the greater the risk of complications. However, there is no solid evidence that cutting down the number or strength of cigarettes smoked significantly reduces the risks to the fetus. Stopping smoking completely as early as possible is a much better option for the health of babies and their mothers.

Pregnancy complications

Some of the pregnancy complications more commonly experienced by women who smoke include:

• Ectopic pregnancy – this is pregnancy outside the uterus, usually in the fallopian tube
• Fetal death – death of the baby in the uterus
• Spontaneous abortion – known as miscarriage
• Problems with the placenta, including early detachment from the uterine wall and blocking the cervical opening (placenta previa)
• Premature rupture of the membranes
• Premature labour.

Effects on the fetus

Every time a pregnant woman smokes a cigarette, her unborn baby is deprived of oxygen and exposed to a cocktail of chemicals, including chemicals that cause cancer.

Some of the many damaging effects of cigarette smoke on the fetus include:

• Reduced oxygen supply due to carbon monoxide and nicotine
• Retarded growth and development
• Increased risk of cleft lip and cleft palate
• Increased heart rate and disruption of the baby’s breathing movements in the womb due to the effects of nicotine.

Problems at birth

Some of the problems caused by maternal smoking include:

• Increased risk of premature birth
• Increased risk of miscarriage and infant death
• Lower birth weight – on average, about 200g less than normal
• Up to three times the risk of sudden unexpected death in infancy (SUDI), which includes sudden infant death syndrome (SIDS) and fatal sleep accidents.

Problems with breast feeding

Over two-thirds of female smokers who quit during pregnancy resume smoking once their babies are born. Some of the problems caused by maternal smoking while breastfeeding can include:

• The chemicals in cigarettes can pass from the mother to the baby through breast milk.
• Smoking reduces the amount of vitamin C in breast milk.
• Smoking can reduce milk production.

Problems for the child in later life

Smoking during pregnancy can impair a child’s health for years to come. Health effects may include:

• Decreased lung function
• Higher incidence of asthma
• Low birth weight, which is linked to heart disease, type 2 diabetes and being overweight in adulthood.

See your doctor if you need help to quit

Ideally, a pregnant woman should stop smoking. In reality, at most only around one in three female smokers quit when pregnancy is planned or confirmed. If you need help, see your health professional for information and advice or call the Quitline on 13 7848 (13 QUIT).

If you are finding it tough to stop smoking, don’t despair. There is evidence to suggest that stopping smoking by the fourth month of pregnancy can reduce some of the risks, such as low birth weight and premature birth.

Nicotine replacement therapy should be monitored

The use of nicotine replacement therapy (such as patches, gum, inhaler and lozenges) during pregnancy hasn’t been adequately researched, so it is unknown what effect these quitting aids may have on the baby. If you are pregnant, it is important to consult your doctor before using nicotine replacement therapies. Pregnant women should also seek assistance from the Quitline and their health professional for alternative quitting methods.

Where to get help

• Your doctor
• Obstetrician
• Quitline Tel. 13 7848 (13 QUIT)

Things to remember

• A woman who smokes while pregnant is at increased risk of experiencing a wide range of problems including ectopic pregnancy, miscarriage and premature labour.
• Babies whose mothers smoke during pregnancy are at a higher risk of having a low birth weight.
• Low birth weight is a risk factor for health problems including infections, breathing difficulties, death and health problems in adulthood.

You might also be interested in:

• Asthma and pregnancy.
  
• Pregnancy - signs and symptoms.
  
• Pregnancy - week by week.
  
• Pregnancy and diet.
  
• Pregnancy and travel.
  

Want to know more?

Go to More information for support groups, related links and references.

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Fact sheet currently being reviewed.
Last reviewed: February 2010

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Smoking while pregnant exposes a woman and her unborn child to an increased risk of health problems including ectopic pregnancy, miscarriage, premature labour and sudden infant death syndrome (SIDS). Passive smoking can also affect a pregnant woman and her child. Discuss alternatives to nicotine replacement therapy with your doctor if you are trying to quit.

Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your qualified health professional. Content has been prepared for Victorian residence and wider Australian audiences, and was accurate at the time of publication. Readers should note that over time currency and completeness of the information may change. All users are urged to always seek advice from a qualified health care professional for diagnosis and answers to their medical questions.

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