Pregnant women who smoke--or who breathe other people's smoke secondhand--endanger the health and life of their unborn child, because the nicotine, carbon monoxide, and other dangerous chemicals in the cigarette smoke pass directly to the fetus. Nicotine is toxic to blood vessels and adversely affects the placenta, promoting premature rupture of the membranes surrounding the baby. Smoking causes spontaneous abortions, stillbirths, and death among newborns, as well as SIDS, 'Sudden Infant Death Syndrome.' Babies of women who smoke also weigh an average six ounces less at birth. There's a link between smoking by pregnant women and the abnormal brain development of fetuses, and it appears to be caused by nicotine. Women who smoke during pregnancy can also increase their babies' risk of developing attention deficit disorder and learning difficulties, as well as increase the chance that they'll pass the virus to their unborn child, if they're infected with HIV. For more information about the risks of smoking during pregnancy, contact a healthcare professional.