Heavy cigarette smoking, meaning greater than one pack per day, during pregnancy can be severely damaging to a developing fetus.
Many studies have shown that babies who are born to mothers that smoke heavily during their pregnancy are born smaller than they would have been had their mothers not smoked. Further, smoking decreases fetal breathing movements - an important index of the fetus' well-being. A recent study found that the IQ's were lower in the babies born to mothers who smoked than a comparable group of babies with non-smoking mothers.
The evidence is overwhelming that if you smoke during your pregnancy, you will hurt your baby's chances of being born healthy and ready to acheive her full potential. So, you can see that it is extremely important that you quit smoking during your pregnancy. Don't take a chance when it comes to the health of your new baby.
And, for your own health and the continued health of your new baby, don't start smoking again after your baby is born. The reports of second-hand smoke effects are incontrovertible.