from the chicks who brought you

dr juuni

all your period questions answered (including the embarrassing ones).

What's the normal age to start periods?

As your gran might say, normal is as normal does. And what that means, is that basically there is no normal. Thanks Gran. But she has a point, because when it comes to starting your periods, normal comes in many guises.

A girl’s first period has a name. It’s called menarche. Here are the stats to kick us off:

  • Most girls start their periods between 11 and 14.
  • The median age – that’s the most common age to start, did you learn nothing in maths?! – is 12.
  • Anything from 10 to 16 is considered well within the normal age range.

Over the past 150 years or so, the start date has been trending younger. Since the 1850s, the average age for menarche (have you noticed how quickly a word starts to sound ‘normal’?) in western societies has plummeted from 15 to 12. And since that’s the average, some people are clearly starting much earlier. Sometimes girls can start as young as seven, which is unusual enough to have its own name – precocious puberty.

The jury’s out on what has caused this general lowering in the age range. Some experts put it down to environmental toxins, while others says it’s a side effect of better nutrition. Or too much nutrition! Because fat tissue contains estrogen, girls who are obese have a higher chance of going through puberty earlier than those who aren’t.

At the other end of the spectrum, if a girl hasn’t had a period by 16, and she's otherwise growing normally and developing breasts and pubic hair, it’s called primary amenorrhoea. Most girls with primary amenorrhoea naturally start their periods by the time they're 18.

Sometimes, starting your periods later than average is just something that runs in the family. So ask your mum and your gran. If it happened to them, it may well happen to you.

The good news is, most scientists agree that when you start your periods has little to no effect on fertility. This may not seem especially interesting when you’re 14, but come 35, these things may be playing on your mind.

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