Prenatal exposure to cigarette smoke and benign breast disease.

BACKGROUND: Experimental studies have indicated that cigarette smoke contains potential human breast toxins and that the toxic influence during the prenatal period is greater than that of later life.
METHODS: The study sample includes 810 women whose mothers enrolled in the Collaborative Perinatal Project between 1959 and 1966 in Boston and Providence. These women have been followed from gestation until middle-age. Information on maternal smoking during pregnancy was prospectively collected during prenatal visits. We identified 146 women who had been told by a health professional that they had benign breast disease. Log-binomial regression models with Generalized Estimating Equation methods were employed to quantify the association between maternal smoking and benign breast disease among offspring.
RESULTS: There was a positive association between maternal smoking during pregnancy and the risk of benign breast disease among offspring. In particular, women whose mother smoked 1 pack or more per day were 1.7 times more likely to develop benign breast disease (relative risk = 1.7 [95% confidence interval = 1.2-2.5]) in comparison with women whose mother never smoked during pregnancy. The association was independent of women's age, race, education, age at menarche, parity, obesity, birth weight, and maternal age at pregnancy.
CONCLUSIONS: Exposure to heavy cigarette smoking during the prenatal period was associated with an increased risk of benign breast disease in adulthood.