hormones word

Why does puberty happen? (A child-friendly explanation)

Inside: So why does puberty happen? It is all to do with hormones and here’s a simple way to explain it to your child.

Have you ever been asked by your child ‘why does puberty happen‘?  Well, it all has to do with hormones.

So how do you go about explaining hormones to your child, without getting all confused yourself? And when you don’t really understand how it all works yourself?

Well, you can take a big breath and relax, because I’m going to take to you on a nice simple tour of how our hormones make puberty happen.

You’ll find more information about puberty in my Puberty 101 page.

Why does puberty happen?

Puberty happens because of your hormones.

Hormones are chemicals that all bodies make. Your body, my body, all bodies.

Hormones travel through your body in your bloodstream, from the place that they are made to the place where they will do their work.

Their job is to start something working. During puberty, the job of some hormones is to make your body capable of reproducing. Which means that you will be able to help make a baby.

So you could think of hormones as little chemical messengers that kickstart puberty ie tell your body to start developing into an adult body.

The pituitary gland

It all starts with the pituitary gland, a small gland that is found at the base of your brain.

One day, when your body says it is ready, your brain will send a message to the pituitary gland, telling it that it’s time to start releasing growth hormones into your bloodstream.

The hypothalamus produces a hormone called gonadotrophin-releasing hormone (GnRH). This hormone stimulates the pituitary gland to release two hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

In males, these hormones travel through your bloodstream to the testicles (testes) to make the hormone testosterone and to start getting ready to make sperm.

In females, these hormones travel through your bloodstream to the ovaries, telling them to start producing the hormones progesterone and estrogen. This causes the egg (ovum) to be released from the ovary.

The pituitary gland is the master gland (the boss) that tells all the other glands what to do. It tells the other glands to start making the hormones that are needed to turn you from being a child to an adult.

Hormones are the chemical messages that allow different parts of the body to communicate with each other. Think of it like a telephone line, where everyone’s telephones are connected by wire cables, and we can send messages (talk) through the telephone lines. The body has its own telephone lines (bloodstream), where the glands are sending hormones (chemical messages) to the different parts of the body.

kids about to start puberty
Prepare your child by letting them know what will soon happen to their body.

What do the hormones do in males?

So why does puberty happen for males? The changes for males are a little different because their body needs to do something different.

Follicle-stimulating hormone

Follicle-stimulating hormone (FSH) has an important job to do. When FSH reaches your testicles, it will start the growth of the seminiferous tubules, which is where your sperm will be made. Over the next couple of years, your testicles will slowly grow bigger, while all this new growth happens inside of them.

This can take a couple of years to happen. Once these tubules are fully grown, your body will then be ready to start maturing the sperm so that they are then ready to help in making a baby. This means that you will be able to ejaculate, and semen, which contains the sperm, will come out of your penis.

Luteinizing hormone

Luteinizing hormone (LH) has a different job to do. It triggers special cells inside your testes, called Leydig cells, to start producing hormones called androgens. The main androgen that the Leydig cells make is called testosterone. Girls have testosterone too, but not as much as boys. Androgens are hormones that tell your body that it’s time to mature or grow up. It helps to make the male changes that boys have, things like a deeper voice, face/armpit/pubic hair, and the start of their sex drive.

Testosterone helps to get certain parts of the body, like the prostate gland and the seminal vesicles, ready to care for and carry the mature sperm. When everything is ready, testosterone will then tell your testicles that it is time to start maturing the sperm to be ready for reproduction via ejaculation. In boys, this means that they will now be able to ejaculate, and semen, which contains the sperm, will come out of their penis.

You can find a more detailed explanation, with diagrams inside my book, Boy Puberty.

What do the hormones do in females?

So why does puberty happen for females? The changes for females are a little different because their body needs to do something different.

Estrogen and Progesterone

These important hormones have different jobs to do. Estrogen is responsible for the growth of your breasts, the changes in your body shape such as hips, legs, and breasts, and the development of your reproductive organs. Together, progesterone and estrogen will prepare your uterus for menstruation (periods) and pregnancy (making a baby).


Your eggs have been inside your ovaries ever since you were a baby growing inside your mother’s uterus.

Estrogen tells your ova (or eggs) to mature. It also tells your ovaries to prepare an egg (ovum) for release into your fallopian tubes. This egg will travel along your fallopian tubes and into the uterus. This whole process of ripening an egg for release from the ovary is called ovulation. Ovulation is when the eggs stored in your ovaries begin to ripen, with one being released every four weeks or so, plus or minus a few days.


While the egg is ripening and getting ready to come out, the lining of your uterus will start to thicken, just in case a sperm joins with your egg, which means it could make a baby. If the egg is joined with a sperm, the body will begin to prepare itself for pregnancy. If the egg is not joined with a sperm, the lining of the uterus will begin to dissolve. This dissolved lining comes out of the vagina, and is known as a period, menstruation or menstrual blood. Two weeks after the period, another egg is released and the whole process of ovulation begins all over again.

You can find a more detailed description, with diagrams, inside my book, Girl Puberty. And don’t forget that boys need to know about periods as well!

3 boys
Boys need to know about periods as well.

Resources to help with talking about puberty

My mission is to create resources that will help you to naturally talk to your kids about sex, all while respecting your personal values.

Which means that inside this website, you’ll find lots of resources to help you with talking to your child about puberty.

My Puberty 101 page includes all of the information on puberty. You’ll find lots of different blog posts to help with talking to your child about growing up.

You’ll find videos about puberty in my Sex Education Videos resource page that you can watch with your child or to learn more about puberty yourself.

You’ll also find an extensive range of children’s books on puberty, for kids of all ages. 

If you get stuck and feel that you need some extra support with talking to your child about puberty, then my book, The Parents’ Guide to Puberty, may be helpful. It’s a straightforward common sense guide that will help you to start having honest conversations that will guide your child through puberty, and strengthen your relationship without feeling embarrassed, awkward or nervous.

Or maybe you’re looking for a video course to sit down and watch together with your child. My friend Rowena from Amazing Me has created a fantastic 2 part interactive course for parents/carers to attend together with their 9 to 12 year old. It’s fun, educational and age-appropriate! You can learn more about her puberty course here.

If you have a child who is expecting their first period, then you may want to consider period pants. Period pants are fantastic for kids who are worried that they won’t know that their period has started until it stains through their clothing for the world to see. My favourite brand for tweens and teens is ModiBodi, as they are good quality and quite absorbent.


If you need some help with explaining sexual intercourse to your child, then How to Talk to Kids About Sex will help you explain sex to your child in a way they will understand. It breaks sex down into simple steps that take the stress out of explaining!

If you’re unsure about how to answer your child’s questions about sex, then I have the perfect book for you! The Sex Education Answer Book will give you age-specific answers to the most common questions kid’s ask parents about sex. Which means you don’t need to worry about finding a child-friendly explanation that your child understands. 

And if you get stuck, feel free to get in touch! You can contact me here.


  • Adolescence and Puberty. Edited by John Bancroft and June Machover Reinisch. 1990. Oxford University Press. New York.
  • Gender Differences at Puberty. Edited by Chris Haywood. 2003. Cambridge University Press. Cambridge.
  • Handbook of Child and Adolescent Sexuality: Developmental and Forensic Psychology. Edited by Daniel S. Bromberg and William T. O’Donohue. 2013. Elsevier. Academic Press. Oxford.
  • Puberty: Physiology and Abnormalities by Philip Kumanov and Ashok Agarwal. 2016. Springer International Publishing. Switzerland.

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