Smoking is harmful to both you and your baby. Carbon monoxide and nicotine in the cigarette are absorbed into your blood stream and cross the placenta. The nicotine will make the baby's heart beat faster, and the baby will get less oxygen. This can affect the baby's growth, and also the development of the lungs through reduced "foetal breathing". After birth the baby is more likely to suffer from asthma and chest infections. The risk of cot death is also increased.