During Pregnancy Carbon monoxide and nicotine in tobacco both reach the baby very easily through the placenta. Both of these can cause problems with the baby's growth and development before birth. Carbon monoxide will reduce the amount of oxygen available in the mother's blood, which can affect the development and size of the baby. Nicotine reduces the amount of oxygen available to the baby and may affect growth and development before birth. Smoking can cause problems in pregnancy such as miscarriage, stillbirth, placental problems, bleeding during pregnancy and premature birth.
Babies practise breathing movements while in the womb.
It has been shown that cigarette smoking can disrupt these breathing movements. The long-term effects of this are still unknown. Research has shown that babies of smokers are generally lighter than babies of non-smokers and that these babies can develop complications such as infections and breathing problems during the first weeks of life. Some research has indicated that smoking may increase the risk of cot death. During pregnancy increased blood volume, as well as upward pressure from the baby pressing upward, can cause breathlessness in many women.