I've given birth to two healty and strong boys.And I smoked during my pregnancy.I asked my mother about this ,since she is a nurse,and she could tell me that what's harmefull is if u use tobakko cause the co2 and nicotine will prevent oxygene intake in the blood.A friend of mine has given birth to 3 healthy children while smoking during her pregnancy. This is what I can tell,hope it helps:-)