Effects of Smoking While Pregnant
Cigarettes contain about 4000 toxic chemicals in them (scary huh!) and every time that you inhale you are bringing them into your body. They reach the baby through the placenta and are also very toxic for your baby.
The main problem is that smoking damages the blood vessels (which is the reason it can cause heart attacks and stokes) and therefore harm the blood vessels of the baby and the placenta. The longer you smoke the more damage it does to the placenta and the more likely it is that your baby will be starving for food and oxygen. This the reason that many babies of smokers are smaller and stressed, and can be born prematurely.
Heavy smoking can cause such damage to the placenta that it becomes detached from your uterine wall and cause the death of your baby (and serious risk for you too). In fact smoking is estimated to be responsible for around 10% of all perinatal infant deaths.
Another major concern is that the baby grows addicted to the nicotine chemical. While the brain is developing in the third trimester studies have shown a link between smoking late in pregnancy and attention deficit disorder (ADD) and other learning disabilities. While the link is not yet conclusive, it is probably wise to avoid risking your baby's brain to nicotine to be on the safe side.
Even if you are lucky and manage to avoid any serious health problems, if your baby has become addicted to nicotine, get ready for a turbulent first few weeks once they are born as the baby becomes increasingly grisly and irritable as they withdraw from the drug.
As a new mother, you are likely to be stressed enough with a new baby, but having to deal with it's addiction withdrawal is not something that I'd wish on anyone!
Overall, the health implications for the baby are far too risky to just hope it won't happen to you. While quitting can be difficult, it is worth trying for your sake and your new child's.
For advice and tips on How to Quit Smoking when Pregnant.