Understanding Puberty: Milestones and Changes in Girls and Boys

Exploring the stages of growing up

Puberty is a stage in a child’s life when their body starts to grow and transform as they move toward becoming an adult. It’s the time when they experience physical changes that allow them to reach sexual maturity. Puberty follows a specific path with a series of physical changes, but the emotional changes may not happen at the same rate. Each child’s journey through puberty is unique, with physical and emotional changes starting and ending at different ages.

Helping your child understand the changes that occur during puberty can give them a better idea of what to anticipate. If you or your child have any worries or questions about the way  puberty is progressing, it can be beneficial to seek guidance from a pediatrician for further support.

In this article, we’ll take a look at development milestones during puberty for boys and girls. During puberty, both boys and girls experience significant physical, emotional, and cognitive changes as their bodies mature and prepare for adulthood. While there can be individual variations, here are some general development milestones for boys and girls during puberty.

What is puberty?

Puberty is triggered by complex hormonal changes that occur in the body. The key trigger for the onset of puberty is the activation of the hypothalamus-pituitary-gonadal (HPG) axis, which involves interactions between the brain, pituitary gland, and reproductive organs. 

Puberty starts when a specific part of your child’s brain, known as the hypothalamus, starts to produce a hormone called gonadotropin-releasing hormone (GnRH). This hormone is then sent from the hypothalamus to a different part of the brain called the pituitary gland. The pituitary gland is stimulated by GnRH to release two additional hormones called luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones travel to the sex organs, such as the ovaries in girls and the testes in boys. Once they reach the sex organs, they trigger the release of sex hormones, namely estrogen in girls and testosterone in boys. These sex hormones act as messengers and bring about the visible signs of puberty.

In girls, the ovaries begin to produce estrogen, which leads to breast development, the growth of pubic and underarm hair, and the start of menstruation. In boys, the testes start producing testosterone, which leads to the growth of the testicles, the development of facial and body hair, the deepening of the voice, and other changes associated with male sexual maturation.

The precise mechanisms that trigger the activation of the HPG axis have yet to be fully understood. However, factors such as genetics, nutrition, body weight, and environmental factors may influence the timing and progression of puberty. Additionally, the onset of  puberty can be influenced by overall health and well-being. 

It is important to note that the timing and progression of puberty can vary among individuals. If there are concerns about the timing or signs of puberty, it is advisable to consult with a healthcare professional for further evaluation and guidance.

When does puberty start for boys?

Typically, boys begin their journey through puberty at some point between the ages of 9 and 14 years old. It’s worth noting that boys generally start puberty approximately two years later than girls. 

If you observe signs of puberty in your son before the age of 9 years old, it would be beneficial to consult your trusted pediatrician regarding these early changes. Similarly, if no signs of puberty have occurred by the age of 15 years old, it would be advisable to discuss this delay with the pediatrician as well.

Developmental milestones for boys

During puberty, boys go through various developmental milestones as they transition from childhood to adolescence. Some of the key milestones include:


  • Growth spurt: Boys experience a rapid increase in height, typically occurring between the ages of 12 and 16 years old.
  • Testicular enlargement: The testicles begin to grow larger and may experience some colour changes.
  • Penis growth: The penis gradually increases in size as puberty progresses.
  • Pubic hair development: Pubic hair starts to grow in the pubic region and becomes thicker and coarser over time.
  • Facial and body hair: Boys may begin to grow facial hair, such as a mustache or beard, and hair in other body areas, including the underarms.
  • Voice changes: The voice deepens as the vocal cords thicken, resulting in a more mature tone. 
  • Muscle development: Boys may notice an increase in muscle mass and strength as their bodies undergo changes during puberty.
  • Acne: Many boys experience the development of acne due to heightened oil production in the skin.


  • Heightened self-consciousness: Boys become more aware of their appearance and body image.
  • Emotional fluctuations: Hormonal changes can cause mood swings and varying emotions.
  • Growing independence: Boys may seek more freedom and assert their independence.
  • Exploring new interests: They may develop new hobbies and explore different areas of interest.
  • Emerging sexual awareness: Boys start experiencing sexual thoughts, feelings, and attraction.

When does puberty start for girls?

On average, girls typically enter puberty around two years earlier than boys. The onset of puberty in girls usually occurs between the ages of 8 and 13 years old. 

The timing of puberty varies among individuals. While some girls may experience early changes known as precocious puberty, others may encounter these changes later, often referred to as delayed puberty. It’s important to recognize that not everyone will go through puberty at the same time. 

Developmental milestones for girls

Puberty is a significant period of development for girls as they transition from childhood to adolescence. Here are some key milestones that girls typically experience during puberty:


  • Breast development: Girls undergo breast development, which may cause tenderness or soreness in the nipples.
  • Growth spurt: Girls experience a significant increase in height, typically occurring between the ages of 10 and 14 years old.
  • Pubic hair growth: Pubic hair starts to grow, gradually becoming coarser and thicker.
  • Menstruation: Girls begin to have their menstrual periods, typically starting between the ages of 9 and 16 years old.
  • Hip widening: The hips gradually widen, and there are changes in body fat distribution.


  • Heightened body image awareness: Girls may become more aware of and concerned about their body shape and size.
  • Emotional shifts: Hormonal changes can result in mood swings, irritability, or heightened sensitivity. 
  • Heightened focus on appearance: Girls may show an increased interest in trying out different styles of clothing, makeup, and hairstyles.
  • Developing new friendships: Social circles expand, and girls may form closer relationships with peers.
  • Developing sexual feelings: Girls begin to experience sexual thoughts, feelings, and attraction.

General tips for parents

When children go through puberty, it can be a challenging and confusing time for both them and their parents. Here are some guidelines to help parents navigate this period:

#1 Provide accurate knowledge

Educate yourself about puberty and equip your child with age-appropriate information about the transformations they will go through.

#2 Foster open dialogue

Create a nurturing and secure environment where your child feels comfortable asking questions and sharing their concerns.

#3 Honour personal space

While it’s crucial to be available, acknowledge and respect your child’s need for privacy during this voyage of self-discovery.

#4 Instill good hygiene habits

Educate your child about proper hygiene practices, including the significance of regular bathing, using deodorant, and tending to their evolving bodies.

#4 Encourage wholesome lifestyle choices

Motivate your child to partake in regular physical activity, maintain a balanced diet, and prioritise sufficient sleep.

#6 Monitor emotional well-being

Stay observant of your child’s emotional health, and if you notice persistent signs of distress or changes in behavior, consider seeking professional assistance.

#7 Seek expert guidance if needed

If you have concerns about your child’s development or if they appear notably ahead or behind in their physical or emotional changes, consult a healthcare professional for further assessment.

Remember, every child is different, and the rate of development can vary widely. It is crucial to provide support, understanding, and a safe space for your kids when they’re dealing with this transitional phase in their lives.

Sources: Healthline, Cleveland Clinic, WebMD