Thank you for downloading the More or Less podcast. We are your guide to the numbers all

around us in the news and in life, and I'm Tim Halford. This week we're looking at the

age at which girls start puberty, and whether it's falling. The New York Times reported

recently that the age when girls begin puberty has fallen by two years, from 14 to 12 since

1990. This sounds like a lot, but should we be worried? And is that figure even right?

Our reporter Josephine Cassley has been looking into this.

This question about whether the age at which girls go through puberty is falling is something

that researchers have been looking into for a long time, and we'll get to all of that.

But let's start by looking at this claim in the New York Times. So it's wrong, and it's

wrong in a couple of different ways, which makes it extra confusing, but also helpfully

highlight some of the challenges of measuring this. I spoke to Dr. Marsha Hermann Giddens.

He's an expert in child health and puberty.

For girls, it's important to make a distinction. A lot of people don't realise the age of

men-arkey, that is, when they start their menstrual period, is mid to late puberty. They're

beginning a puberty. It was usually in girls the beginning of rest developments, or what

we call breast-biting.

With this stat, they seem to have confused the two. 12 to 14 is around the age when girls

are expected to have their first period. Puberty starts before that. But whether we're

talking about the onset of puberty or a girl's first period, this drop of two years in the

last three decades seems way too high. I've not found any evidence to support it, and

actually it's contradicted by much of the New York Times' own reporting on this. However,

that's not the end of the story, because even though this estimate seems high, many people

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