By BCPP Director of Science Rainbow Rubin, PhD, MPH

A June 5, 2024, BBC news article by David Cox explains how new research shows that girls in the US are getting their first periods earlier. Exposure to toxic air is partly to blame.

American girls today have been estimated to start menstruation up to four years earlier compared to girls living a century ago. In May, new data showed that while girls born between 1950 and 1969 typically began menstruating at 12.5 years, this decreased to an average of 11.9 years for the generation born in the early 2000s. These trends were more pronounced among those who were Black, Asian, or of other races compared with non-Hispanic White individuals and among low socioeconomic groups. Early puberty has been repeatedly associated with a higher risk of diseases ranging from breast and ovarian cancers, metabolic syndromes such as obesity and type 2 diabetes, and cardiovascular disease. Some of the major culprits appear to be toxic gases such as sulphur dioxide, nitrogen dioxide, carbon monoxide and ozone, all of which are released into the air either through vehicle emissions, coal-burning power plants, or waste produced by manufacturing plants.

About the Study

Menarche and Time to Cycle Regularity Among Individuals Born Between 1950 and 2005

This cohort study of racially and ethnically diverse US individuals born between 1950 and 2005 examines temporal trends in menarche and time to regularity.