Motherhood and smoking

Statistics

• Around 23% of women who were pregnant/breastfeeding in 2001 were smokers. For all women aged 20-39, around 26% of women aged smoke regularly (daily or weekly).
• In Australia round 58,000 babies are born to mothers who smoked throughout their pregnancy.

For 11% of women, being pregnant or wanting to start a family is a factor that motivates them to change their smoking behavior.

While a substantial number of women continue to smoke during pregnancy, many reduce the number of cigarette they smoke or attempt to quit once they find out they are pregnant.

Approximately 20-30% of women who were smokers quit when they find out they are pregnant, the majority quit within the first three months of pregnancy. They quit because they are concerned about the health of the baby, and secondly their health. Some women may quit as they prepare to become pregnant and many others quit as soon as they learn that they are pregnant.

There is strong evidence that women return to smoking once the baby is born. Usually they stop for around five to seven months. Half of all pregnant women who quit go back to smoking within six months of the baby being born, and approximately 70% return to smoking once the baby is a year old.

How do the chemicals in cigarette smoke affect babies?

Nicotine and carbon monoxide are the main chemicals that cause problems during pregnancy. Carbon monoxide is attracted to elements in the baby's blood even more so than the blood of the mother, this significantly reduces the ability of the foetus to carry oxygen. The oxygen carried by the baby's blood is bound more tightly to the red blood cells, which means that less oxygen is released into the baby's tissues.

A number of chemicals in tobacco smoke that cross the placenta are known carcinogens.

Nicotine also crosses the placenta raising foetal blood pressure and affects the baby's ability to practice breathing movements. Nicotine is also found in the breast milk of women who smoke and breastfeed.

Women who smoke during pregnancy are:

• Twice as likely than nonsmokers to have a baby which is of low birth weight – low birth weight is an important risk factor for health problems in newborn babies, including still birth and complications in infancy. They are lighter because they do not develop fully.
• More than twice as likely to have a baby whose growth has been retarded as a result of smoking, this means the baby is born when it is not fully developed.
• One third more likely to have a baby that is born prematurely.
• Nearly three times more likely to have a baby that dies from SIDS.
• An increased risk of miscarriage, the risk is increased by one third.
• An increased risk of stillbirth, the risk is increased by one third.

Smoking during pregnancy accounts for:

• 11% of all ectopic pregnancies (where the pregnancy occurs in the fallopian tube and results in miscarriage)
• 9% of all miscarriages (spontaneous abortions)

The risk of miscarriage increases with the number of cigarettes smoked and the age the mother commenced smoking.

• 15% of all antepartum hemorrhage (bleeding from the vagina 24 weeks to up until birth)
• 21% of all premature rupture of the membranes (early breaking of the waters)
• 23% of all low birth weight babies (low birth weight means under 2,500 gms)
• 9% of stillbirths
• 34% of all SIDS deaths

Impact on hospitals of smoking during pregnancy in Australia, 1992

Holman et al 1995

Pregnancy and quitting

Women who quit smoking before pregnancy reduce the risk of:

• Delay in becoming pregnant - rates of conception in ex-smokers is similar to those who have never smoked
• Infertility - ex-smokers appear to have little excess risk of fertility.

Women who quit during pregnancy reduce the risk of:

• Premature breaking of the waters around the baby
• Delivery before the due date
• Low birth weight
• Stillbirth and death in the month after birth

Quitting at any time during the pregnancy improves the health outcomes for both the mother and the baby.

Passive smoking, babies and children

Babies exposed to tobacco smoke are more likely to:

• die from Sudden Infant Death Syndrome (SIDS or cot death)
• have serious chest illnesses such as pneumonia, croup, bronchitis and bronchiolitis
• be admitted to hospital.

The more smoke the child is exposed to, the more likely it is that it will suffer health problems due to passive smoking.

Children exposed to tobacco smoke are more likely to:

• suffer from asthma
• have worsened symptoms and more asthma attacks if they already have asthma
• contract 'glue ear' (otitis media), an infection and swelling of the ear, which is the most common cause of hearing loss and surgery in children
• be infected with meningococcal disease, which can sometimes cause death, mental disability, hearing loss or loss of a limb
• have slightly poorer lung function and development, so they cannot breath as hard or with as much breath compared to children of non-smokers
• have lung complications if they undergo surgery under anaesthesia
• miss school due to illness
• snore, have sore throats, wheeze and cough, more often.

Prolonged exposure to other people's cigarette smoke can cause lung cancer and heart disease in adults. The processes causing these diseases can start in childhood.

Health cost of smoking during pregnancy

A recent study examined the costs conferred by involuntary smoking, which mainly occurs in the young. The report, which examined costs in 1998/99, includes the cost of diseases caused by smoking during pregnancy and exposure of babies, children and young people under the age of 15 to tobacco smoke.

Involuntary smoking in those under the age of 15 is estimated to total 103 deaths, account for 75,311 bed days and cost hospitals $43 million.

References

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9. National Cancer Institute. Health effects of exposure to environmental tobacco smoke: a report of the California Environmental Protection Agency. Smoking and Tobacco Control Monograph No. 10. Bethesda, MD: U.S. Department of Health and Human Service, National Institutes of Health, National Cancer Institute, NIH Pub No 99-4645, 1999.
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11. Royal College of Physicians of London. Smoking and the young. A report of a working party of the Royal College of Physicians. London: Royal College of Physicians of London, 1992.
12. Collins D, Lapsley H. Counting the cost: estimates of the social costs of drug abuse in Australia in 1998-99. Monograph Series No 49. National Drug Strategy. Commonwealth Department of Health and Ageing, Canberra 2002.