How does cigarette smoking by mothers affect their unborn children?
Cigarette smoke contains more than 2,500 chemicals, with nicotine, tar, and carbon monoxide thought to be the most dangerous to the fetus. Smoking has been associated with a number of pregnancy complications. One is an increased risk of ectopic pregnancy. In an ectopic pregnancy, the embryo becomes implanted in a fallopian tube or other abnormal site instead of the uterus. With the rarest of exceptions, these pregnancies do not result in the birth of a baby, and must be removed surgically or with drug treatment to protect a woman’s life. Cigarette smoking also appears to double a woman’s risk of developing placental complications (which occur in about 1 percent of pregnancies). These include placenta previa, a condition in which the placenta is attached too low in the uterus and covers part or all of the cervix; and placental abruption, in which the placenta separates from the uterine wall before delivery. Both can result in a delivery that jeopardizes the life of mother and baby. Smok
