Breast Health

Do Larger Infants Raise Breast Cancer Risk?

Women who give birth to large infants may be 2.5 times more likely to develop breast cancer than women who give birth to the smallest babies.

The reason may be pregnancy hormones.

Photo of pregnant woman with daughter kissing her abdomen

Researchers at the University of Texas Medical Branch at Galveston looked at data from two studies involving a total of more than 24,000 women. They found that women who gave birth to the largest babies - those in the top quintile - were more likely to have a high concentration of estriol, alpha-fetoprotein and plasma protein-A, all of which are present during pregnancy.

More hormones

The larger the infant, the higher the concentration of these hormones in the pregnant mother.

High levels of some of these hormones also encourage breast cancer to develop.

"Women can't alter their pregnancy hormones, but they can take steps to increase their general protection against breast cancer," says Radek Bukowski, M.D., the study's lead author.

Lowering the risk

He points to breastfeeding, having more than one child, healthy eating, and exercise as proven ways to lower the risk of getting breast cancer.

The study was published in the journal PLoS ONE. Although it found an association between hormone levels, infant birth weight, and breast cancer risk, researchers say more studies are needed to prove a cause-and-effect relationship.

Always talk with your health care provider to find out more information.

Online Resources

(Our Organization is not responsible for the content of Internet sites.)

American Cancer Society - What are the risk factors for breast cancer?

National Cancer Institute - Breast Cancer Prevention

Susan G. Komen Foundation - Understanding Prevention

September 2012

Screening for Breast Cancer

Breast cancer that's caught early is easier to treat. You can be screened for breast cancer through these two main tests:

  • Clinical breast exam (CBE). This exam is done by your doctor during a regular checkup. He or she will feel both of your breasts and underarm areas for lumps or other changes. The American Cancer Society recommends CBEs at least every three years for all women in their 20s and 30s and annual CBEs for women 40 and older.

  • Mammography. A mammogram is a special kind of X-ray that helps find breast tumors before symptoms of cancer appear. During the test, your breast is placed between two metal or plastic plates that flatten and spread the tissue. Low levels of radiation are used to take a picture of the inside of your breast. Some facilities have digital mammography, which shows results on a computer, rather than on film. The test can be uncomfortable, but it only lasts a few moments.

Each woman's risk is different. Talk with your doctor about when you should begin breast cancer screening.

Always talk with your health care provider to find out more information.

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