Tobacco Control and Smoking

Fact Sheet 4: You are not the only one smoking this cigarette

Smoking during pregnancy reduces the growth and health of babies and increases the risks of a number of complications and illnesses for both the mother and baby.

In New Zealand in 2006, around 22 percent of pregnant women reported they smoked while pregnant.¹

Quitting smoking before or during pregnancy, and avoiding exposure to second-hand smoke, will have a positive impact on the health of both the mother and the unborn baby. It will also reduce the likelihood of related health problems for the child after birth.

Babies born to women who smoke during pregnancy have a greater chance of premature birth, low birth weight, stillbirth, and infant mortality.² Smoking during pregnancy can also affect the development of babies' lungs, which increases the risk for many health problems.^2,3

Nicotine and other chemicals in tobacco smoke are passed onto the baby through the placenta. Nicotine causes the blood vessels to constrict which decreases the amount of oxygen going to the unborn baby and is an important contributor to low birth weight.⁴ Mothers who smoke also pass nicotine onto their babies through their breast milk.⁵

Smoking during any stage of pregnancy increases the risk of premature birth. Australian research shows that in 2003, for babies of mothers who smoked, the likelihood of pre-term birth was 60 percent higher than in babies of mothers who did not smoke.⁶

Low birth weight is a leading cause of infant death⁵ and an important risk factor for a number of health problems and complications in infancy and childhood.

The Australian research also showed that babies of mothers who smoked were twice as likely to be of low birth weight than babies of mothers who did not smoke. On average, babies born to smoking mothers weigh about 200 grams less than those born to non-smoking mothers.⁶

Mothers who smoke are 50 percent more likely to have a stillborn baby than mothers who do not smoke.⁶ This risk is believed to be influenced by smoking-induced placental complications combined with smoking-induced abnormal foetal growth.⁶

In addition, babies born to mothers who smoke before and after birth are three times more likely to die from Sudden Infant Death Syndrome (SIDS).^2,3

It has been estimated that around 50 New Zealand babies die every year from SIDS as a result of exposure to second-hand smoke,⁷ and emerging evidence suggests that smoking during pregnancy is an even stronger risk factor for SIDS than exposure to second-hand smoke. ⁸

Some of the long-term health effects on the development of children born to smoking mothers include:

• Allergies – fourfold increased risk of having allergic skin diseases by 18 months of age.⁴
• Higher blood pressure in childhood. ⁴
• A much greater risk of childhood respiratory disorders such as asthma and wheezing. ⁴
• Increased risk of obesity in childhood and into adolescence.⁹ According to a recent study, Australian children of mothers who smoked while pregnant are approximately 42 percent more likely to be obese by their early teens than children of mothers who did not smoke while pregnant.^9,10

In addition to avoiding smoking while pregnant it is also important for pregnant women to avoid exposure to second-hand smoke as this can harm unborn babies. Maternal exposure to second-hand smoke may result in premature birth and lower birth weight for their babies.

There is emerging evidence that the risk of some childhood cancers increases as a result of the mother's exposure to second-hand smoke during pregnancy. Other studies suggest that children of fathers who smoke have an increased risk of developing childhood cancers, possibly as a result of damage to the father's sperm.³

Want to quit smoking? The most important thing is to make a quit attempt. For help, talk to your doctor, pharmacist, quit smoking provider or call the Quitline on 0800 778 778 or visit The Quit Group web site at www.quit.org.nz