Girls’ periods are earlier and more irregular than previous generations

Is it true that girls in the United States, especially girls of color, are getting their periods earlier than previous generations?

A new study of 71,341 women supports growing concern that the age at which girls start menstruating is getting younger, and the trends are even more pronounced for certain racial and ethnic groups. The findings also suggest that many girls and young women have experienced irregular cycles for years, a risk factor for a variety of health problems, including cardiovascular disease, metabolic diseases such as diabetes, and certain types of cancer.