A new study this week adds to the growing body of evidence that girls in America are reaching

puberty earlier with potentially troubling implications for their long-term health.

More girls are getting their first periods sooner than previous generations

and experiencing longer periods of menstrual irregularity as well. We're

joined now by the senior author of that study, Dr. Shruthi Mahalangaya, assistant professor at the

Harvard, TH Chan School of Public Health.

Dr. Welcome and thanks for joining us.

Thank you.

So let me just tick through some highlights of your study real quick here.

You found there that girls are now, or rather were getting their first period on average at the

age of 12 and a half between 1950 and 1969. Now between 2000 and 1969.

Now, between 2000 and 2005,

that's down to 11.9 years old.

You also found the percentage of girls

getting their period before the age of 11 almost doubled from about 8.5 to 15

and a half and the percentage of girls getting their period before the age of 9

more than doubled. Dr. why is this significant and worth paying attention to?

Sure, the age at the first period and time to cycle regularity are two aspects of menstrual health.

It is really, really important to understand are two aspects of menstrual health.

It is really, really important to understand this trend

for a variety of reasons.

One of the most important reasons is that both of these

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