Up to 13 percent of women still smoke during their pregnancies. Cigarette smoke contains over 4,000 chemicals, all of which enter the blood stream and head straight for your baby. Two of these in particularcarbon monoxide and nicotinenarrow the blood vessels in the umbilical cord. Since this is the babys source of oxygen, when this happens it becomes much harder for him to breathe. Oxygen deprivation in the womb can lead to stillbirth, premature delivery, low birth weight, learning disorders and a lower IQ. If youre a non-smoker, but your partner lights up, your baby is still subjected to serious risks. In fact, the CDC says that women exposed to secondhand smoke have a 20 percent greater chance of delivering underweight babies than women who arent exposed. Even women who spend a great deal of time around wood fires may experience similar negative effects due to inhalation of carbon monoxide. This risk, however, is smaller than the risk of smoking, and not something to be worried about if it occurs in moderation. If youre pregnant and cant stop smoking, talk to your doctor about quitting. If you can do so by week 14, youre about as likely as anyone to have a healthy baby!