1. Pre-teens
  2. Development
  3. Physical development

Physical changes in puberty: girls and boys

9-15 years

Puberty is a time of big changes inside and outside your child’s body. It helps to know about the major physical changes in puberty that you can expect for girls and boys, and when these changes happen.

What is puberty?

Puberty is the time when your child moves through a series of significant, natural and healthy changes. These physical, psychological and emotional changes signal your child is moving from childhood to adolescence

Changes in puberty include:

When does puberty start?

Puberty starts when changes in your child’s brain cause sex hormones to start being released in girls’ ovaries and boys’ testes.

This usually happens around 10-11 years for girls and around 11-13 years for boys.

But it’s normal for the start of puberty to range from 8-13 years in girls and 9-14 years in boys. Every child is different.

There’s no way of knowing exactly when your child will start puberty. Early changes in your child’s brain and hormone levels can’t be seen from the outside, so it’s easy to think that puberty hasn’t started.

Puberty can be completed in about 18 months, or it can take up to five years. This range is also completely normal. 

You can support your child during puberty by talking about puberty, supporting healthy eating and physical activity, and encouraging healthy sleep routines.

Girls: key physical changes in puberty

If you have a daughter, these are the main external physical changes in puberty that you can expect.

Around 10-11 years

  • Breasts will start developing. This is the first visible sign that puberty is starting. It’s normal for the left and right breasts to grow at different speeds. It’s also common for the breasts to be a bit tender as they develop. If your child wants a bra, a soft crop top or sports bra can be a good first choice.
  • Your daughter will have a growth spurt, and she’ll get taller. Some parts of her body – like her head, face and hands – might grow faster than her limbs and torso. This might leave her looking out of proportion for a while. On average girls grow 5-20 cm. They usually stop growing at around 16-17 years.
  • Your daughter’s body shape will change. For example, her hips will widen.
  • Your daughter’s external genitals (vulva) and pubic hair will start to grow. Her pubic hair will get darker and thicker over time.

Around 12-14 years (about two years after breast development starts)

  • Hair will start growing under your daughter’s arms.
  • Your daughter will get a clear or whitish discharge from her vagina for several months before her periods start. If the discharge bothers your daughter, you could suggest she uses a panty liner. If your daughter says she has itching, pain or a bad or strong odour, check with a GP.
  • Periods will start. This is when the lining of the uterus (womb), including blood, is shed every month. Your daughter might get pain before and during her period, like headaches or stomach cramps. Her periods might be irregular at first.

Boys: key physical changes in puberty

If you have a son, these are the main external physical changes in puberty that you can expect.

Around 11-13 years

  • The external genitals (penis, testes and scrotum) will start to grow. It’s normal for one testis to grow faster than the other. You can reassure your son that men’s testes usually aren’t the same size.
  • Pubic hair will start to grow. It will get darker and thicker over time.

Around 12-14 years

  • Your son will have a growth spurt. He’ll get taller and his chest and shoulders will get broader. Some parts of his body – like his head, face and hands – might grow faster than his limbs and torso. This might leave him looking out of proportion for a while. On average boys grow 10-30 cm. They usually stop growing at around 18-20 years.
  • It’s common for boys to have minor breast development. If your son is worried by this, you can let him know it’s normal and usually goes away by itself. If it doesn’t go away or if your son’s breasts seem to be growing a lot, he could speak to his GP.

Around 13-15 years

  • Hair will start growing on other parts of your son’s body – under his arms, on his face and on the rest of his body. His leg and arm hair will thicken. Some young men will grow more body hair into their early 20s.
  • Your son will start producing more testosterone, which stimulates the testes to produce sperm.
  • Your son will start getting erections and ejaculating (releasing sperm). During this period, erections often happen for no reason at all. Just let your son know that this is normal and that people don’t usually notice. Ejaculation during sleep is often called a ‘wet dream’.

Around 14-15 years
The larynx (‘Adam’s apple’ or voice box) will become more obvious. Your son’s larynx will get larger and his voice will ‘break’, eventually becoming deeper. Some boys’ voices move from high to low and back again, even in one sentence. This will stop in time.

The start and stages of puberty happen at different times for different children. But if you’re worried that your child is starting puberty early or late, it’s a good idea to talk to your GP.

Other physical changes in puberty: inside and out

Brain
Changes in the teenage brain affect your child’s behaviour and social skills. Your child will begin to develop improved self-control and skills in planning, problem-solving and decision-making. This process will continue into your child’s mid-20s.

Bones, organs and body systems
Many of your child’s organs will get bigger and stronger. Lung performance improves, limbs grow, and bones increase in thickness and volume.

Clumsiness
Because children grow so fast during puberty, their centres of gravity change and their brains might take a while to adjust. This might affect your child’s balance. You might see a bit more clumsiness for a while, and your child might be more likely to be injured.

Physical strength
Muscles increase in strength and size during this period. Your child’s hand-eye coordination will get better over time, along with motor skills like ball-catching and throwing.

Weight
Your child will gain weight and need more healthy food. Teenagers’ stomachs and intestines increase in size, and they need more energy, proteins and minerals. Foods with plenty of calcium and iron are important for bone growth and blood circulation.

Sleep patterns
Sleep patterns change, and many children start to stay awake later at night and sleep until later in the day. Also, the brain re-sets the body clock during puberty. Children going through puberty need more sleep than they did just before puberty started.

Sweat
A new type of sweat gland in the armpit and genital area develops during puberty. Skin bacteria feed on the sweat this gland produces, which can lead to body odour. Hygiene is important.

Skin and hair
Glands in the skin on the face, shoulders and back start to become more active during puberty, producing more oil. This can lead to skin conditions like acne. If you’re concerned about your child’s skin, first check whether the pimples or acne are worrying your child too. If they are, consider speaking with your GP.

Your child might find her hair gets oilier, and she needs to wash it more. This is normal.

Teeth
Children will get their second molars at around 13 years. Third molars – ‘wisdom teeth’ – might appear between 14 and 25 years. These teeth can appear in singles, pairs, as a full set of four wisdom teeth – or not at all. Healthy teeth and gums are vital to your teenage child’s health, so teenage dental care is important.

Puberty and children with additional needs

Children with additional needs are likely to go through the physical changes of puberty in the same way as other children.

Some children might have delayed physical development because of chronic health problems, which might cause a delay in the onset of puberty. How your child manages puberty emotionally might also be affected by additional needs. A health professional can answer any questions you might have about this.

Video

Puberty and children with autism spectrum disorder

6:06

This short video is about puberty and autism spectrum disorder (ASD). You’ll find out why it’s a good idea to talk about puberty early with your child with ASD to give her time to adjust to changes. You’ll also hear from parents who share their stories and experiences of supporting children with ASD who are going through puberty.

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Last updated or reviewed
11-12-2017

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Raising Children Network is supported by the Australian Government. Member organisations are the Parenting Research Centre and the Murdoch Childrens Research Institute with The Royal Children’s Hospital Centre for Community Child Health.

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