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. Smoking also may in-crease a woman's risk of miscarriage. Both can result in a delivery that jeopardizes the life of mother and baby, though a cesarean delivery can prevent most deaths. Placental problems contribute to the slightly increased risk of stillbirth that is associated with smoking.
Cigarette smoking can cause reproductive problems before a woman even becomes pregnant.
Studies show that women who smoke may have more trouble conceiving than nonsmokers. Smoking also causes changes in a man's sperm that may reduce his fertility. Children who are exposed to cigarette smoke before birth also may be at increased risk of lasting problems, including asthma. Children of mothers who smoked during pregnancy also may be at increased risk of learning and behavioral problems. One recent study found that boys whose mothers smoked during pregnancy were four times more likely than sons of nonsmokers to have serious behavioral problems.