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Menstrual History

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Women who started menstruating (having periods) younger than age 12 have a higher risk of breast cancer later in life. The same is true for women who go through menopause when they're older than 55. Over the past 15 years, girls have been starting puberty at younger ages. Breast development has started even earlier than menstrual periods. This unexpected shift has been attributed to the obesity epidemic and broad exposure to hormone disruptors, since a rise in hormones triggers the onset of breast development and puberty. The age when women go through menopause, however, has stayed about the same.

The earlier your breasts form, the sooner they're ready to interact with hormones inside and outside your body, as well as with chemicals in products that are hormone disruptors. This longer interaction with hormones and hormone disruptors can increase risk.

Also, when girls start menstruating at a younger age, the time between breast development and a first full-term pregnancy is usually longer than when menstruation happens later. During this time, breast tissue tends to be immature, overactive, and particularly sensitive to hormonal influences.

The longer a woman menstruates, the higher her lifetime exposure to the hormones estrogen and progesterone. All of these factors are associated with a higher risk of breast cancer later in life.

Steps you can take

While you can't control when you start and stop menstruating, you can make lifestyle choices that can keep your risk as low as it can be:

These are just a few of the steps you can take. Girls who maintain a healthy weight and exercise regularly may be able to prevent early puberty. Review the links on the left side of this page for more options.


TPLG Booklet ThumbnailThink Pink, Live Green: A Step-by-Step Guide to Reducing Your Risk of Breast Cancer teaches you the biology of breast development and how modern life affects breast cancer risk. Download the PDF of the booklet to learn 31 risk-reducing steps you can take today.


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