Drinking alcohol before first pregnancy is likely to boost a woman's risk of breast cancer later in life, U.S. researchers said Wednesday.

Previous studies have looked at breast cancer risk and alcohol consumption later in life or at the effect of adolescent drinking on noncancerous breast disease. However, the link between alcohol consumption during the period of time between a woman's first menstrual period and first pregnancy and the risk of breast cancer had not been reported.

According to researchers from the Washington University School of Medicine in St. Louis, breast tissue is particularly susceptible to carcinogens during that period of time.

They analyzed data from 116,671 female registered nurses, aged 25 to 44, on medical history, reproductive history, and lifestyle.

With the exclusion of women who did not meet the predetermined study criteria, 91,005 women with a history of full-term pregnancy were included in the final analysis. Among these women, 1,609 cases of breast cancer and 970 cases of benign breast disease occurred during the study period.

The researchers reported in the Journal of the National Cancer Institute that "the longer the duration of menarche (first period) to first pregnancy, the higher is a woman's risk of breast cancer. "

Compared with nondrinkers with a shorter duration, nondrinkers with duration of 10 or more years between menarche and first pregnancy had 26 percent and 81 percent increased risk of breast cancer and proliferative benign breast disease respectively, they said.

According to the study, for every daily drink a young woman takes, she increases her lifetime risk of breast cancer by 13 percent.

The study also found that for every bottle of beer, glass of wine or shot of liquor consumed daily, a young woman increases her risk of proliferative benign breast disease by 15 percent. Although such lesions are noncancerous, their presence increases breast cancer risk by as much as 500 percent.

"Parents should educate their daughters about the link between drinking and risk of breast cancer and breast disease," lead author Ying Liu said. "That's very important because this time period is very critical."

The researchers said the findings call for more research into what young women can do to counteract alcohol's adverse effects if they choose to drink. Past studies that didn't consider alcohol use suggest that eating more fiber and exercising more lowers cancer risk for everyone.