How does menstrual and reproductive history affect breast cancer risks?
Women who began their menstrual cycles before age 12, or have no biological children, or had their first child at 30 or older, or began menopause after 55 are at a higher risk. This means that research has proven that the number of menstrual cycles a woman has over time influences risk.
For women with several of these factors, their risk is higher than for those with just one of these risk factors.
Medically reviewed June 2023