The longer the mother smokes during pregnancy, the greater the effect on the infant s birth weight. Women who smoke are less likely to breast-feed their infants than are women who do not. However, smoking during pregnancy appears to have decreased from 1989 through 1998. Women who quit smoking before or during pregnancy reduce the risk for adverse reproductive outcomes, including difficulties in becoming pregnant, infertility, premature rupture of membranes, preterm delivery, and low birth weight. Most relevant studies suggest that infants of women who stop smoking by the first trimester have weight and body measurements comparable with those of nonsmokers infants.
Studies also suggest that smoking in the third trimester is particularly detrimental.
Women are more likely to stop smoking during pregnancy, both spontaneously and with assistance, than at other times in their lives. Using pregnancy-specific programs can increase smoking cessation rates, which benefits infant health and is cost effective. However, only one-third of women who stop smoking during pregnancy are still abstinent 1 year after the delivery.