One week you’re convinced your period’s coming, and then something feels off. The timing’s strange, so you start to wonder: ...

A female’s first menstrual period, known as menarche, occurs during puberty. Menstruation indicates that the body is mature enough for reproduction. About 98% of girls begin their periods by age 15.

Girls in the U.S. are getting their first menstrual period about 6 months earlier on average than they did in the 1950s and '60s. And more girls are beginning menstruation before the age of 9, which ...

Your period could be crampin’ your style — and your future health. Girls are reaching puberty faster than previous generations, a phenomenon perplexing researchers. The average age of the start of ...

Girls in the U.S. are getting their first period earlier than in decades past. Researchers say there are multiple factors causing early puberty, including obesity and environmental pollutants. Girls ...