News Release

May 11, 2004

Contact: Kristina Goodnough, 860-679-3700

Alcoholic Drinks During Pregnancy May Increase Female Offspring’s Risk of Breast Cancer

Study with Rats Suggests Caution for Women, Says Researchers

FARMINGTON, CONN. - Daughters born to women who drink alcohol during their pregnancy may have a greater risk of breast cancer, based on a study using animals published this month in the British Journal of Cancer.
For their study, researchers fed pregnant female rats diets containing no alcohol, a low amount (16 grams) or a moderate amount (24 grams) of alcohol per kilogram of feed between days 7 and 19 of pregnancy. Adult female offspring of the rats exposed to alcohol during pregnancy developed significantly more breast cancers than the female offspring of rats that were not given alcohol during pregnancy.

“The alcohol exposure that increased breast cancers was significantly lower than the alcohol exposures that induce fetal alcohol syndrome in animal models, giving additional weight to the recommendation that women should avoid consuming any alcohol during pregnancy,” said William Shoemaker, Ph.D., associate professor of psychiatry at the University of Connecticut Health Center and one of researchers who conducted the study.

“The amount of alcohol that increased breast cancer risk was quite low,” said Shoemaker. “Before this experiment, I would have said that a single daily alcoholic drink by a pregnant women might not be a significant hazard to her child. I wouldn't say that now, based on our research.“

The study was lead by Professor Leena Hilakivi-Clarke of the Oncology Department at Georgetown University with the collaboration of Shoemaker and Richard G. Stevens, Ph.D., from the Department of Community Medicine at UConn Health Center.

While diet has long been studied for a link to breast cancer risk, there is little evidence for any strong effects. Alcohol is an exception. “There is a consensus that alcohol intake increases the risk of developing breast cancer,” researchers said in the study. “Some epidemiological studies suggest that alcohol drinking during adolescence and early adulthood has the strongest impact on breast cancer risk, while results of some studies indicate that drinking later in life increases breast cancer risk most. Data obtained in the present study suggest that alcohol exposure in utero through a pregnant mother may increase breast cancer risk.”

Drinking alcohol can increase a woman’s circulating estrogen levels. Researchers concluded alcoholic drinks and elevated estrogen levels during pregnancy program fetal mammary glands to change in form and in gene expression. Specifically, alcohol may increase mammary tissue density and the number of terminal end buds in mammary glands that are later targets for malignant transformation.

“The alcohol consumption during pregnancy resulted in no obvious effects on the offspring at birth,” says Stevens. “The babies were born the same size and weight as babies born to mothers who weren’t fed alcohol. It was later in life that the rat babies exposed to alcohol in utero developed breast tumors.”

UConn Health includes the schools of medicine and dental medicine, the UConn Medical Group, University Dentists, and John Dempsey Hospital. Home to Bioscience Connecticut, UConn Health pursues a mission of providing outstanding health care education in an environment of exemplary patient care, research and public service. More information about UConn Health is available at

Note: News professionals are invited to visit the UConn Health Today news page ( for regularly updated news and feature stories, photos and media stories. News releases are archived at UConn Health news and information is also available on Facebook, Twitter and YouTube.