By outdoor-nature-child.com According to recent statistics, the average age of first menstruation for girls born in the U.S. between 2000 and 2005 is 12 years old. This trend comes amid a concerning increase in breast cancer rates among women under 50, which have risen by at least 15% over the past two decades. The most common type of breast cancer is estrogen receptor-positive (ER+), where cancer cells react to estrogen, leading to the development of tumors influenced by this hormone.
Reports from NBC highlight that the spike in ER+ breast cancer cases is largely attributed to younger women. Some medical professionals suspect that this phenomenon is linked to the earlier onset of menstruation and the trend of delayed childbirth among American women.
Dr. Alexandra Thomas, an oncologist at Duke Health, stated, “Women are exposed to numerous sources of estrogen throughout their lives, which could be a significant factor. However, we still don’t understand why we are seeing these changes occur at such an earlier age.”
Researchers speculate that multiple factors may contribute to this situation, including obesity, alcohol consumption, genetics, and hormonal birth control methods. The earlier onset of puberty in girls has gained attention for its potential role in increasing cancer risk.
For decades, the age of onset of puberty among girls has been declining, especially among African American and Asian American populations. Dr. Adetunji Toriola of the Siteman Cancer Center at Washington University remarked, “Our work is still in the early stages, but previous studies have suggested that certain reproductive factors may be associated with breast cancer development.”
A study published in late March in JAMA Network Open reveals that women born between 1950 and 1969 experienced their first menstruation at an average age of 12.5, with less than 9% starting before 11. In contrast, girls born between 2000 and 2005 began menstruating at an average age of 12, which is a shift from previous generations. Additionally, the rates of early menstruation and very early onset have increased by 15.5% and 1.4%, respectively.
Dr. Eleonora Teplinsky, Director of Women’s Oncology at Valley Health System in New Jersey, shared, “If menstruation starts before age 11, the risk of developing breast cancer is higher, and we’re seeing a consistent decline in the average age of first menstruation among girls today.”
Moreover, women are tending to have children at older ages or choosing not to have children at all. Ann Partridge, co-founder and director of the Program for Young Adults with Breast Cancer at Dana-Farber Cancer Institute, noted that while pregnancy might temporarily elevate a woman’s breast cancer risk, it can slightly reduce the long-term risk.
Partridge explained that women experience amenorrhea during pregnancy, but “this is not related to estrogen.” Instead, the changes in breast tissue after giving birth may contribute to increased breast cancer risk among women who have children later in life.