Sexual Development

While the foundation for a person’s sexual development and sexual health starts at birth and continues throughout childhood, there are many changes—sexual, physical, emotional, social and developmental—that occur at the beginning of puberty and throughout the teen years.

By informing yourself about the changes to expect during puberty and adolescence, you’ll be better prepared to talk to your child about the changes they will experience, ensure they understand that they are normal and healthy, and answer questions they have openly, honestly and correctly.

The information below will outline some information on puberty, menstruation and human sexual response.


Puberty is the time where sexual organs mature and having a baby becomes possible. Puberty, and the changes involved, happen at different times for different people. Females tend to go through puberty earlier than males. Females may experience puberty changes between the ages of 8 and 16, while males will go through it sometime between the ages of 12 and 18. Every person is different, and puberty can happen earlier or later. It may be a fast process for some people, and a very gradual one for others. Overall, puberty usually lasts 3 or 4 years. For information on the emotional, social and developmental changes your child will experience, click here.

Here are some physical and sexual changes your child can expect. Give your child the facts about their body and an understanding of puberty—this will help them to understand that these changes are normal and healthy before it happens.

Both Females and Males

  • they will start growing taller and will gain weight (both fat and muscle)
  • their skin will start making more oil and acne on their face, upper back and/or chest
  • they will grow hair on their legs, underarms and pubic area, and this will continue to grow thicker and darker during puberty
  • they will start to sweat more and may need to start using antiperspirant/deodorant
  • they will have a new desire for sexual experiences which are brought on by changes in hormones.
  • they may masturbate

Females Only

  • they will grow taller faster than most of the boys, and will usually reach their adult height by age 16 or 17
  • their breasts will start to grow and they may experience soreness under the nipples
  • they will start to gain weight in their hips, buttocks, legs and stomach
  • their menstrual period will start and will eventually become regular—usually females get their period 2 to 2.5 years after their breasts start to grow
  • they will start to have white, mucous-like discharge from their vagina

Males Only

  • their shoulders will grow wider
  • body hair and facial hair will start to grow
  • their penis, scrotum, and testes will grow
  • ejaculation and nocturnal emissions (‘wet dreams’) occur and sperm production begins or continues
  • voice starts to crack and becomes deeper
  • they may have swelling under the nipples (this growth usually goes away by the end of puberty)
  • they are capable of erections and ejaculation (sometimes during sleep) as sperm production begins


Menstruation, also known as ‘having your period’, is a physical change that females will experience during puberty. At some point during puberty, the body begins to release one egg from their ovaries each month. If this egg were fertilized by male sperm, it would grow into a baby. To prepare for the fertilized egg, the uterus builds up a thick lining of blood and tissue. This lining is where the fertilized egg would grow into a baby. If the egg is not fertilized by sperm, the egg and the lining of the uterus leaves the body through her vagina and the process starts all over again. This is called a menstrual cycle. It takes place over a month (approximately 23-35 days). A period is a term that refers to the time during which blood and tissue are draining though the vagina. It usually lasts between 3 and 5 days.

Everyone is different. This process depends on a person’s height and weight, and other factors. There is no right or wrong time for when menstruation will begin. Females will begin getting their periods sometime during puberty. Here are a few things to discuss so your child can be prepared:

  • talk about menstruation with your child before their periods start. Emphasize that periods are a normal process of growing and changing and they can continue with usual activities. Explain that the bleeding will last for a few days.
  • use a calendar or diary to keep track of their cycle. This will help you both to plan for the next one.
  • when your child first starts menstruation they may have a period and then not have another one for a few months. A regular cycle of around 28 days usually settles down after a year or so.
  • have a supply of pads ready to show your child. Try demonstrating on a doll. Moms or sisters may also want to demonstrate.
  • talk to your child about what premenstrual syndrome (PMS) is and what they might experience. For example, some teens get cramps that can be quite uncomfortable. Using a hot water bottle and/or taking ibuprofen (Advil) may help.
  • keep a hygiene pack (clean underwear, pads, wipes) in a nearby place (backpack or locker) to help with unexpected periods
  • discuss the importance of hygiene and cleanliness, in particular changing pads regularly
  • think about clothing choices (don’t wear white pants when your period is due)

Human Sexual Response

Human sexual response is a series of physical and emotional changes that happen as a person becomes sexually aroused.

Here are some common examples of what may happen when a person becomes aroused:

  • erection: an erection is when the tissues of the penis fill with blood making it larger and harder
  • masturbation: masturbation is when you touch your own genitals to make them feel good. Some people choose to masturbate while others choose not to. Either choice is normal.
  • nocturnal emission (wet dream): a wet dream is when a male’s penis gets erect or hard, and ejaculates or releases semen while he is asleep. Wet dreams can happen to both boys and grown men. A sign that a male has had a wet dream is waking up in damp pyjamas and bed sheets. This may be embarrassing, but it is normal. Wet dreams are a sign of growing up.

Helpful Tools


A Hard Pill to Swallow

Julie accidently drops something she wishes her dad hadn’t seen. How does dad respond? Watch our webisode to find out; and learn how to start the conversation on sexual health.


The Hair Down There

Ryan asks mom about ‘the hair down there’ for the first time. How will she respond? Watch our webisode to find out; and learn how to start the conversation on sexual health.

Back to top