Currently, about 13 percent of pregnant women in the U.S. smoke during pregnancy. If all pregnant women in the U.S. stopped smoking, there would be an estimated 10 percent reduction in infant deaths, according to the U.S. Public Health Service. Cigarette smoke contains more than 2,500 chemicals. It is not known for certain which of these chemicals are harmful to a developing fetus. How-ever, both nicotine and carbon monoxide are believed to play a role in causing adverse pregnancy outcomes.
Smoking nearly doubles a woman's risk of having a low-birthweight baby.
These health consequences can be devastating, inflicting major emotional as well as economic costs on families, and on communities. Low birthweight can result from poor intrauterine growth, preterm delivery, or a combination of both. Smoking has long been known to slow fetal growth. However, if a woman stops smoking by the 16th week of pregnancy, she's no more likely to have a low-birthweight baby than a woman who never smoked. Even if a woman has not been able to stop smoking in her first or second trimester, stopping during the third trimester can still improve her baby's growth.