Smoking during pregnancy is linked to numerous negative outcomes, including low birth weight, sudden infant death syndrome, and increased risk for attention deficit disorder, conduct disorder, and nicotine use in offspring. Despite this extensive literature, it is estimated that 13%-30% of women in the United States continue to smoke while pregnant. Now, a new 40-year longitudinal study provides strong evidence that prenatal exposure to maternal stress hormones predicts nicotine dependence later in life — but only for daughters.