Smoking while pregnant is not a good combination. Cigarettes contain dangerous chemicals such as tar, carbon monoxide, and nicotine that can increase the risk of pregnancy complications which is also fatal to the baby. If you cannot quit smoking for your health, think about the baby. Smoking during pregnancy increases the risk of the baby having weaker lungs, low birth rate and a higher risk of SIDS (Sudden Infant Death Syndrome). Miscarriage and premature labor can also happen and the more cigarettes you smoke, the more complications there will be. The only way to avoid these from happening is to stop smoking as early as possible.