There are a lot of good reasons to quit smoking, but isn't your baby the most compelling? Researchers agree that smoking during pregnancy can be a leading contributor to a range of health problems, both for the mother and the baby.Smoking during pregnancy increases the amount of nicotine and carbon monoxide, both poisonous, in the mother's bloodstream. These chemicals restrict the blood vessels and limit the amount of oxygen and nutrients traveling to the placenta, the tissue that nourishes th.