Smoking at any time in a person’s life causes many health risks. In Canada today, young women are more likely than any other group to start smoking. When these women begin having babies, they risk the health of their children every day they continue to smoke.
Pregnancies are deeply and negatively affected by smoking, including second hand smoke. A pregnant woman who smokes risks two lives, her own and her baby’s. In particular, infants of smokers are more likely to die of SIDS. Children of smokers are more likely to suffer from asthma, lung and ear infections, and miss time from school. They are also more prone to behaviour problems and ADD (Attention Deficit Disorder). Studies have shown that they have an average IQ of 15 points less than the children of non-smokers!
With each inhalation, tar compounds build up in the woman’s lungs. Nicotine and other toxic substances, such as cyanide, sulphide, carbon monoxide and cancer-causing hydrocarbons, enter her blood stream. These substances pass through the barrier of the placenta (the baby’s life support system) to the fetus (unborn baby). In the baby’s system, these substances often reach higher levels than in the mother.
Nicotine reduces the amount of blood flowing to the uterus and the baby inside by 30 to 40 per cent. This means the baby is not getting the nutrients and oxygen it needs. This is one way that smoking interferes with normal growth of the baby. It also directly affects the developing lungs and brain, resulting in short or long-term changes.
Smoking appears to trigger the release of a stress hormone in the baby. Each time a cigarette is smoked, this hormone makes the baby’s heart rate increase. The carbon monoxide that accumulates with smoking forms a compound that interferes with the release of oxygen to the baby.
We may not be aware of all of the harmful effects that smoking has on pregnancy, but what we do know is frightening.
Smoking contributes to infertility, so smokers may have more difficulty getting pregnant than non-smokers. Smokers are also more likely to have a miscarriage, stillbirth, premature delivery, severe bleeding in pregnancy, and disturbed growth in the baby.
Table 1: Complications of pregnancy associated with smoking
|Intrauterine growth restrictAion (IUGR)
||The baby does not grow to its full potential while in the uterus (womb) and is smaller than normal.|
|Placental abruption||The placenta separates partly or completely from the wall of the uterus. This can result in a large blood loss, death of the baby and sometimes the mother.|
|Placenta previa||The placenta lies partly or completely over the cervix. This can result in a large blood loss, death of the baby and sometimes the mother. Delivery is usually by caesarean section.|
|Prematurity||The baby is born much earlier than expected, may require special care and may suffer long-term effects.|
|Prelabour rupture of membranes (PROM)||The sac of water around the baby breaks or leaks before the start of labour.|
|Deep vein thrombosis and pulmonary embolus||Blood clots may form in the mother’s veins and pieces of clot may break off and go to her lungs.|
|Hypertension in pregnancy||High blood pressure during pregnancy.|
|Stillbirth||Death of the baby before birth.|
|Fetal intolerance to labour||During labour, the baby does not cope with the stress of contractions. The labour is more likely to require interventions like forceps or caesarean section.|
If all pregnancies were smoke-free, the rate of low birth weight babies would be half what it is now. However, smaller babies do not necessarily mean an easier delivery.
The baby is small because her blood supply has been reduced. This increases the chance of trouble in labour. Interventions that may be needed include:
By delivering a healthy baby that has grown to its full potential, a mother is more likely to avoid these problems.
No! While quitting may be stressful for the mother, and the baby may feel some stress, it is not nearly as stressful as continuing to smoke. Ideally, women should quit before they get pregnant to grow the healthiest babies. Still, studies show that quitting in early pregnancy can undo the risks caused by smoking.
The more cigarettes smoked during pregnancy, the more complications occur as a result. For this reason, even if she cannot quit completely. A pregnant woman should try to cut down as much as possible.
Using nicotine patches or gum during pregnancy to assist with quitting is controversial because nicotine can harm the developing baby. Some doctors feel that if a woman cannot quit alone, using nicotine aids temporarily is better than continuing to smoke. Many resources are available to women who wish to quit. Talk to your family doctor or pharmacist. You can also find details on www.familyhealthonline.ca (search ‘quit smoking’).
Second hand smoke is also a concern. A woman exposed to a large amount of tobacco smoke is affected to the same degree as a woman who is a light smoker. Family, friends and co-workers should not smoke around pregnant women. Women who are pregnant should avoid smoky environments as much as possible. If a mother continues the habit after pregnancy, second hand smoke can affect her baby’s health.