Even one alcoholic drink a day in the years before a woman's first pregnancy can increase her risk of breast cancer later in life, according to a large new study.
Other research has linked alcohol consumption to increased breast cancer risk, as well as finding that delayed childbearing can increase breast cancer risk.
The new research is thought to be the first to focus on the effect of alcohol intake during the time frame between the start of menstruation and a first pregnancy, the researchers said.
"The risk increased by 11 percent for every 10 grams a day of intake, about six drinks per week," said study author Dr. Ying Liu, an instructor of public health sciences at Washington University School of Medicine, in St. Louis. "These risk values were estimated as compared with nondrinkers."
"One drink was defined as one bottle or can of beer, a 4-ounce glass of wine or a shot of liquor," Liu said.
About one drink a day also increased the risk for proliferative benign breast disease, a risk factor for breast cancer, by about 16 percent, according to the study, published in the Journal of the National Cancer Institute.
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