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Smoking during pregnancy is associated
with a number of adverse maternal and fetal outcomes. It has been associated with placenta
previa, abruptio placenta, premature rupture of membranes, preterm delivery, intrauterine
growth restriction, Sudden Infant Death Syndrome (SIDS), and increased perinatal mortality
rates. Because so many women smoke (26 percent of women of reproductive age in the United
States and 20 percent of pregnant women), smoking represents a major public health
problem. Little is known about the nature of the dose-response relationship between
tobacco exposure and these outcomes. Relationships are assumed to be linear, but this
assumption has often been based on studies in which tobacco exposure has been defined
categorically. |