What Age Do Girls Start Their Period – And Why Is It Getting Earlier?

Girls are getting their first periods earlier and earlier. Scientists have identified a few key reasons why the onset of puberty is happening at a younger age.

When do most girls get their period? The average age for girls to get their first menstrual cycle has been steadily dropping over the years. In 1928, the average age for American girls to get their period was 13.9. In the 1950s and 60s, this number dropped to 13.5, then to 12.8 in the 1970s. Today, the average age to get your period sits at around 12.5 years old.

This might not seem like a huge jump, but it’s still a steady decline that should be noted, especially when there are girls getting their period as young as 7 or 8 – known as precocious puberty. Sounds crazy to me, but this happens to about 15% of girls today. I could barely comprehend what a pad or tampon was at the age of 13, let alone 7. I set out to find out why exactly this is happening because hello, I’m curious, and I know you are too (if you weren’t, you wouldn’t be here).

While I found no definitive answers, scientists have identified a few key reasons why the onset of premature puberty in girls is happening at a younger age. I’m going to go over the main reasons.

Obesity and early puberty

In 2013, the Childhood Obesity Foundation found 42 infants and young children were overweight or obese worldwide. In 2025, there will be 70 million overweight or obese infants and young children, if the current trend continues. That is insane.

Now, you might be wondering how exactly this relates to the onset of your period, so let me explain. Fat cells make estrogen, so the more fat cells you have, the more estrogen you have in your body. If you’ve been checking out our previous blog posts or our Instagram (I hope you have been!), you know that estrogen is what makes your uterine lining thicken. When the lining of your uterus thickens and isn’t fertilized with an egg, it will begin to shed and voila: period.

There are a few things you can do to combat this. Of course, there are medical reasons that contribute to weight gain as a child, and sometimes there’s not a ton that can be done (at least, not without a doctor). But overall, make sure your kids are eating well and getting lots of exercise. I know 4-year olds spending more time using an iPad or watching television than paying attention to their surroundings, and that’s a bad habit to get into. Don’t go taking away your kids’ electronics, but make sure the have a balance in their lives.

Image via Instagram (@tonyfutura) 

Stress and periods

There’s an extensive amount of research that relates chronic stress to the onset of early puberty in girls, leading to their first period. The idea is that chronic stress is perceived by the brain as a low-grade threat, which triggers the brain to start reproduction. Wild, right?!

Keep in mind, when I say ‘chronic stress,’ I’m not referring to stress related to homework or friends. While this could play a part, scientists found this form of stress was most common in young girls who are dealing with their parents divorcing, or young girls who are victims of sexual or domestic abuse. It’s a little hard for me to give advice on this one, but I would say make sure you have open lines of communication with your children. In my experience, most kids will say exactly what’s on their mind, but sometimes we need to ask them.

Image via Instagram (@littledrill) 

Environmental factors

If weight and stress don’t seem to be contributing factors, it could be an environmental trigger. There isn’t a huge amount of data surrounding this theory, and the data that does exist is pretty unclear.

Basically, we’re exposed to tons of different chemicals daily, mainly through the air, and they have the ability to speed up the puberty process in girls – and the onset of your first menstrual cycle. Our air is much more polluted than it was back in the day, and there are so many different chemicals in the air that scientists can’t pinpoint exactly what chemical might be causing periods to arrive earlier.

While we can’t figure out exactly what the cause of premature puberty is, this should be some more encouragement to fight climate change and save the environment!

Image via Instagram (@littledrill)

Signs your daughter is about to start her period

When a young girl hits puberty, some of the classic signs include body hair, a bigger/fuller chest and an increase in sweat. For signs your daughter’s period may be starting, read the last bit of our most recent blog post, here.

Image via Instagram (@tonyfutura) 

So basically - no, there isn’t a definitive reason why someone would get their period at 7 years old. I would like to stress that it’s not unhealthy to get your period at a young age, it’s more inconvenient, sucky and annoying. However, it does draw some attention to some bigger issues, like obesity, sexual and domestic violence and the environment. The moral of the story here is we need to take care of ourselves, our loved ones, and the planet we call home!

For some extra protection when Aunt Flo next comes to town, try out a pair of our teen period panties for comfort and peace of mind.

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