How does menstrual and reproductive history affect breast cancer risk?

By NBCF team

Last updated on Aug 26, 2026

Medically reviewed on Jan 31, 2026

by: Lillie D. Shockney, RN, BS, MAS, HON-ONN-CG

Studies show certain menstrual and reproductive factors are associated with breast cancer risk. Therefore, a woman’s menstrual and reproductive history can affect her breast cancer risk.

The following factors may increase a woman’s risk of developing breast cancer:

• Menstrual history: Starting menstrual periods early, usually before the age 12, and entering menopause later, usually after the age of 55, may slightly increase breast cancer risk. These factors are associated with a longer lifetime exposure to certain hormones, such as estrogen and progesterone.
• Reproductive history: Having a first full-term pregnancy after the age of 30, not breastfeeding, and never having a full-term pregnancy may be associated with a higher risk.

Menstrual and reproductive history are considered alongside other breast cancer risk factors, such as age, family history, genetics, and lifestyle. Having one or more of these risk factors does not mean that someone will develop breast cancer..

Sources:
Centers for Disease Control and Prevention (CDC)