Stages of puberty: what happens to boys and girls

Puberty is when a child’s body begins to develop and change as they become an adult. Girls develop breasts and start their periods, and boys develop a deeper voice and start to look like men.

The average age for girls to begin puberty is 11, while for boys the average age is 12. But there’s no set timetable, so don’t worry if your child reaches puberty before or after their friends. It’s completely normal for puberty to begin at any point from the ages of 8 to 14. The process takes about four years overall.

Late or early puberty

Children who begin puberty either very early (before the age of 8) or very late (after 14) should see a doctor to rule out an underlying medical condition.

Read more about puberty problems.

This page covers:

• Signs of puberty in girls
• Signs of puberty in boys
• Mood changes during puberty
• Puberty support for children
• Puberty support for parents and carers

First signs of puberty in girls

• The first sign of puberty in girls is usually that their breasts begin to develop. It’s normal for breast buds to sometimes be very tender or for one breast to start to develop several months before the other one
• Pubic hair also starts to grow and some girls may notice more hair on their legs and arms.

Later signs of puberty in girls

After a year or so of puberty beginning, and for the next couple of years:

• Girls' breasts continue to grow and become fuller.
• Around two years after beginning puberty, girls usually have their first period. Read more about starting periods.
• Pubic hair becomes coarser and curlier.
• Underarm hair begins to grow. Some girls also have hair in other parts of their body, such as their top lip. This is completely normal.
• Girls start to sweat more.
• Girls often get acne – a skin condition that shows up as different types of spots including whiteheads, blackheads and pus-filled spots called pustules.
• Girls have a white vaginal discharge.
• Girls go through a growth spurt. From the time their periods start, girls grow 5-7.5 cm (2-3 inches) annually over the next year or two, then reach their adult height.
• Most girls gain weight – and it’s normal for this to happen – as their body shape changes. Girls develop more body fat along their upper arms, thighs and upper back; their hips grow rounder and their waist gets narrower.

After about four years of puberty in girls

• Breasts becomes adult-like.
• Pubic hair has spread to the inner thigh.
• Genitals should now be fully developed.
• Girls stop growing taller.

First signs of puberty in boys

• The first sign of puberty in boys is usually that their testicles get bigger and the scrotum begins to thin and redden.
• Pubic hair also starts to appear at the base of the penis.

Later signs of puberty in boys

After a year or so of puberty starting, and for the next couple of years:

• The penis and testicles grow and the scrotum gradually becomes darker. Read more about penis health.
• Pubic hair becomes thicker and curlier.
• Underarm hair starts to grow.
• Boys start to sweat more.
• Breasts can swell slightly temporarily – this is normal and is not the same as "man-boobs".
• Boys may have "wet dreams" (involuntary ejaculations of semen as they sleep).
• Their voice "breaks" and gets permanently deeper. For a while, a boy might find his voice goes very deep one minute and very high the next.
• Boys often develop acne – a skin condition that shows up as different types of spots, including whiteheads, blackheads and pus-filled spots called pustules.
• Boys go through a growth spurt and become taller by an average of 7-8cms, or around 3 inches a year, and more muscular.

After about four years of puberty in boys

• Genitals look like an adult’s and pubic hair has spread to the inner thighs.
• Facial hair begins to grow and boys may start shaving.
• Boys get taller at a slower rate and stop growing completely at around 16 years of age (but may continue to get more muscular).
• Most boys will have reached full adult maturity by 18 years of age.

Mood changes in puberty

Puberty can be a difficult time for children. They're coping with changes in their body, and possibly acne or body odour as well, at a time when they feel self-conscious.

Puberty can also be an exciting time, as children develop new emotions and feelings. But the "emotional rollercoaster" they’re on can have psychological and emotional effects, such as:

• unexplained mood swings
• low self-esteem
• aggression
• depression

For more information on what to expect and how to handle puberty-related mood changes, read our articles on teen aggression, coping with your teenager and talking to your teen.

Puberty support for children

If children are worried or confused about any part of puberty, it may help them to talk to a close friend or relative.

• ChildLine’s website answers boys' common questions about puberty and girls' common questions about puberty. It also offers free and confidential advice on its telephone helpline, which can be reached on 0800 1111. Children can also look at its puberty message board for girls and puberty message board for boys to see what other young people are asking about.
• 4You is a leaflet for boys and girls that explains body changes at puberty, sex and how babies are made, in a down-to-earth way.
• "Periods - what you need to know" is an FPA (formerly the Family Planning Association) leaflet that is helpful for older girls who are just about to or have just started their periods.
• Contact a Family’s booklet "Growing up, sex and relationships" is for disabled children.

Puberty support for parents and carers

• "Surviving Adolescence – a toolkit for parents" is a leaflet that gives parents and carers clear information on what to expect when children hit adolescence, including why they’re likely to become sulky, suddenly start dieting, have crushes on friends, and crave excitement.
• The FPA (formerly the Family Planning Association) has a range of online leaflets that give advice on talking to your children about growing up, sex and relationships.

Starting periods

Most girls start their periods when they're about 12, but they can start as early as 8, so it's important to talk to girls from an early age to make sure they're prepared before the big day.

Many parents feel awkward talking about periods, especially with pre-teen girls, who can seem to get easily embarrassed.

One way round this is to respond to questions or opportunities as they arise. David Kesterton, who organises the FPA's Speakeasy courses – which teach parents how to talk to their children about puberty, sex and relationships – says clear speaking and down-to-earth, age-appropriate language is key.

Best age to talk about periods

"Parents often ask me when the right age to talk to girls about starting periods is, and I recommend that it should be an ongoing process rather than a formal sit-down talk.

"You can use TV ads for tampons, or buying sanitary towels at the supermarket, for example, to start the conversation with girls about periods. Or simply ask your daughter what she already knows and go from there.

"Whenever possible, use clear language, like 'vagina', even though you may feel uncomfortable using these words. Emphasise that periods are completely normal and natural – they're part of growing up and all women have them.

"And don't forget boys. They, too, need to learn about periods. Talk to them in the same way as girls about the practicalities, mood changes that can come with periods, and the biological reason behind periods, and it will keep them informed, as well as help them to understand what girls go through each month."

When a girl starts her periods it's a sign that her body is now able to have a baby. It's important that she also knows about getting pregnant and contraception.

The questions girls ask about periods

Here are some of the questions that you, as a parent, might get asked by girls about periods, with suggestions on how to answer them:

How will I know when my periods are soon going to start?

Signs that your period is on its way are if you've grown underarm and pubic hair. Typically, you'll start your periods about two years after your breasts start growing and about a year after getting a white vaginal discharge. The average girl will get her first period around 12 years old, but it varies from person to person.

Why haven't my periods started yet?

Your periods will start when your body is ready. That's usually between the ages of 10 and 16.

See a GP if your periods haven't started by age 16 (or 14 if there are no other signs of puberty either).

Possible reasons include being underweight, doing lots of exercise (including dance, gymnastics and athletics) and a hormone imbalance.

Read more about 'why haven't I started my periods?'

How do I get ready for my first period?

Talk to your mum or another adult you trust about what you can expect before it actually happens.

It's a good idea to start carrying sanitary pads or tampons around with you in advance, so you aren't scrambling to find some when your period finally arrives.

If you find yourself at school without a pad or tampon, talk to a female teacher or the school nurse. They're used to being asked and they'll want to help you out.

How long will my first period last?

When your first period arrives it might not last very long, as it can take your body some months to get into a regular pattern. As a general rule, once they're settled, you'll have a period every 28 to 30 days and it will last three to seven days.

How much blood will I lose?

It might seem a lot, but it's only about three to five tablespoons. It's not a sudden gush – you'll just see a reddish-brown stain on your pants or on your sheets when you wake up in the morning.

What if period blood leaks through my clothes?

Part of becoming a woman is dealing with embarrassing mishaps. There are ways of covering up stains until you're able to change your clothes, such as tying a sweatshirt around your waist.

Keep a spare pair of pants and tights at school or in your bag, and avoid wearing light-coloured trousers and skirts during a period, just in case.

Should I use pads or tampons?

This is really up to you. Both tampons and towels or pads are safe and suitable for girls who have just started their periods. You'll probably want to use pads for your very first period, though, as tampons can take a bit more getting used to. It might be worth experimenting until you find the product that suits you best.

Can a tampon get lost inside me?

No, it can't. When you insert a tampon, it stays in your vagina. All tampons come with a string at one end that stays outside your body. You can remove the tampon at any time using this string.

Read the full answer here: Can a tampon get lost inside me?

What if I forget to remove my tampon?

If you forget to remove your tampon, it can turn sideways or become compressed at the top of your vagina. This can make it difficult or impossible for you to pull it out. If you think you've left a tampon in and you can't get it out, go to your GP. They can remove it for you.

Read the full answer here: What if I forget to remove my tampon?

Further reading for girls

• "Periods – what you need to know" is an FPA leaflet that uses cartoons and speech bubbles to explain periods and how to use tampons and towels. Helpful for older girls who are just about to or have just started their periods.
• "Susan’s Growing Up" is a picture book about periods that has been specially developed for people with learning disabilities. It’s from the Books Beyond Words series from the Royal College of Psychiatrists.
• The easyhealth website has four leaflets on periods that are ideal for explaining menstruation to a girl with learning difficulties. "Help! I've started my period", "What is that in my pants?" and "What about tampons?" are all free to read online or to print out.
• "The Period Book: Everything You Don’t Want to Ask (But Need to Know)" by Karen Gravelle, and published by Piatkus, is a well-known book for any girl approaching puberty. It explains what to expect and how to cope with periods.

Read more articles on the menstrual cycle.

Boys and puberty Q&A

Puberty is the process of growing from a boy into a young man. Here's what to expect.

Scroll down to watch a video on puberty

When will I start puberty?

If puberty hasn’t started yet, don’t worry. Most boys begin when they’re around 13 or 14 years old, but some start earlier and some later.

We all grow and change at different rates, and there’s nothing you can do to make it happen sooner or later. Your body will change when it’s ready.

It’s normal to feel confused or worried sometimes. It can help to talk to someone you trust, such as your dad, mum, brother or a trusted teacher.

What will happen to my body?

There are plenty of signs that puberty has started. Every boy is different, but here are some of the most common changes to look out for:

Getting taller

Your body grows, and it may become more muscular.

Bigger penis and balls

Your testicles and penis grow, and they may feel itchy or uncomfortable.

Unexpected erections

Your body produces more hormones, so you might get erections when you least expect them.

Spots and sweat

Hormones can make you sweaty and spotty, but as long as you have good personal hygiene, you can still look and feel healthy.

Read about acne.

Wet dreams

You start producing sperm, and you may have wet dreams in which you ejaculate (release fluid containing sperm out of your penis) while you're asleep. This is normal.

Hair growth

Areas of your body become more hairy, including your armpits, legs, arms, face, chest and around your penis.

Deeper voice

As your voice begins to break, you might sound croaky for a while, or you might have a high voice one minute and a low voice the next. It will settle down eventually.

Mood swings

You may have mood swings and feel emotional, but your feelings will settle down in time.

For more information, read the boys’ bodies Q&A, which includes answers to questions about penis size and sperm.

Girls and puberty Q&A

Puberty is when a girl grows up into a young woman. Every girl goes through it, but it can be a tough time. Here are the changes to expect.

Watch a video on puberty

When will I start puberty?

Puberty usually starts between the ages of 8 and 14, but every girl is different. We all grow and change at different rates, and there's nothing you can do to make it happen sooner or later. Your body will change when it's ready.

Your breasts may grow quickly or slowly. You might have your first period, then not have another one for months. There's no such thing as "normal", so don't panic if your experience is different from other girls.

If you feel confused, you're not the only person. Try talking to someone you trust, such as your mum, dad, sister, friends, or a teacher.

What will happen to my body at puberty?

During puberty, it's normal to experience the following changes:

Growing taller

You'll get taller, and this might happen quite quickly.

Breasts and hips get bigger

Your breasts and hips get bigger. You might feel itchy or uncomfortable when this happens. This is normal.

Hair grows on your body

Hair grows under your arms and around your vagina. Some girls develop hair on other parts of their body, such as their top lip. This is normal.

Periods start

Your periods will start at some point during puberty. You might get period pains before or during your period. Find out more about periods.

Vaginal discharge begins

You may notice your vagina produces vaginal discharge (fluid). This is normal. It's your vagina's way of keeping clean and healthy. The discharge should be colourless or white, and shouldn't smell. If it looks green or yellow and smells, see a doctor as you might have an infection.

Spots and sweat appear

Hormones can make you sweaty or spotty, but as long as you have good personal hygiene, you can still look and feel healthy. Find out about acne.

Feelings go up and down

You might have mood swings and feel emotional, but your feelings will settle down eventually.

Find out more about girls' bodies, including breast size, dealing with periods, pregnancy and sex.

Girls' bodies Q&A

Puberty can be a confusing time – your body and your feelings are changing as you grow up. Here are answers to some of the questions girls ask about their bodies.

Click on the questions below to go directly to the answer.

• At what age do you go through puberty?
• Is discharge from the vagina normal?
• My discharge smells. Is that normal?
• When should you start your periods?
• What should you use when your period starts?
• Is my period normal?
• What if my period is late?
• Are my breasts too small?
• How do I know if I have breast cancer?
• When do I have to have a cervical screening test?
• What is the hymen?
• Do you put on weight when you're on the Pill?
• Can you get pregnant if you have sex during your period?
• What is the clitoris?

At what age do you go through puberty?

You'll probably start to notice changes from age 10 upwards, but there's no right or wrong time to start. Some people go through puberty later than others. This is normal. If you have no signs of puberty by the age of 16, see a doctor for a check-up.

Find out more about girls and puberty.

Before puberty, most girls have very little discharge. After puberty, what's normal for one girl won't be normal for another. Some produce a lot of fluid and some produce very little.

When you start your periods, you'll probably notice your discharge varies at different times during your menstrual cycle. It might be colourless or creamy white in colour, and it may become more sticky and increase in quantity.

Find out about periods and the menstrual cycle.

My discharge smells. Is that normal?

It's not normal if your vaginal area is itchy or sore. These symptoms may mean you have an infection, such as thrush, which is common and easily treated.

If the discharge becomes smelly or green and you've had sex without using a condom, there's a risk you might have a sexually transmitted infection (STI).

If your discharge is different from what's normal for you, see a doctor or nurse. Advice is free and confidential, even if you're under 16.

Read about how to keep your vagina clean and healthy.

When should you start your periods?

Girls usually start their periods between the ages of 10 and 16. Most girls start when they're around 12. As everyone develops at different rates, there's no right or wrong age for a girl to start.

Your periods will start when your body is ready, and there's nothing you can do to make them start sooner or later.

If you haven't started your periods by the time you're 16, visit your doctor for a check-up.

Watch a video about the menstrual cycle.

What should you use when your periods start?

To be prepared for your first period, keep sanitary pads (sometimes called sanitary towels) or tampons at home, and carry some in your bag.

Both tampons and pads are safe and suitable. You may want to use pads for your very first period, though, as tampons can take a bit more getting used to.

Sanitary pads line your underwear to soak up the blood as it leaves your vagina. Tampons are inserted inside the vagina to soak up the blood before it leaves the vagina. Tampons have a string that hangs outside the vagina, and you pull this to remove the tampon.

Don't flush sanitary pads or tampons down the toilet. Wrap them in paper and put them in the bin. Most women's toilets have special bins for sanitary products.

There are different kinds of pads and tampons for light, medium and heavy blood flow. Use whatever you find most comfortable. Try different kinds until you find one that suits you. You might need to use different kinds at various points during your period. You need to change your pad or tampon several times a day.

You'll find instructions in the packet on how to use them. Sanitary pads and tampons are available in pharmacies, supermarkets, and some newsagents and petrol stations.

There's a life-threatening infection called toxic shock syndrome (TSS), which affects around 20 people – men and women – in the UK every year. It's not known why, but a lot of these cases occur in women who are wearing tampons, particularly highly absorbent (heavy) ones.

If you're worried about anything to do with periods or want more information, talk to an older woman, such as your mum, big sister, the school nurse or a teacher. Your doctor or local contraception or young people's clinic can also help. Find sexual health services near you.

Is my period normal?

Don't worry if your periods aren't the same as your friends' periods. Every girl is different. Bleeding can last up to eight days, although it usually lasts about five days. The bleeding is heaviest during the first two days.

During your period, your blood flow may seem heavy, but the actual amount of blood is equivalent to between 5 and 12 teaspoons. However, you may have periods that are heavier than normal. This is known as menorrhagia, and there's medication to treat it, so talk to your doctor if you're worried. You can also take the heavy periods self-assessment to see if your periods are heavy.

The average length of the menstrual cycle (from the first day of your period until the day before your next period) is 28 days, although anywhere between 24 and 35 days is common.

Your hormone cycle may affect you physically and emotionally. Some women don't have any symptoms, but on the days leading up to your period you may have symptoms of premenstrual syndrome. These include:

• headaches
• bloating
• irritability
• backache
• feeling depressed
• a general feeling of being upset or emotional
• difficulty sleeping
• difficulty concentrating
• breast tenderness
• some weight gain (up to 1kg)

Once your period has started, these symptoms usually improve. They disappear when your period has ended.

Periods can sometimes be painful. The precise cause of painful periods is unknown, but you may feel pain in your abdomen, back or vagina. It usually starts shortly before your period begins and lasts for a few days. Painkillers can help.

Find out more about treating painful periods.

What if my period is late?

If you're worried about your period, visit your doctor or a local community contraceptive or young persons clinic – call the national sexual health helpline on 0300 123 7123 for details.

Girls' periods can be irregular for many different reasons, including stress. Another reason for a late period is pregnancy. If you've had sex without using contraception and your period is late, take a pregnancy test as soon as possible.

You can get a test kit from your local doctor, contraceptive clinic or young person's clinic. You can also do a pregnancy test yourself using a test kit bought at a pharmacy or supermarket.

Find sexual health services near you.

Are my breasts too small?

No. Every woman is different, and everyone's body develops at its own rate. Don't worry about what size is "normal".

How do I know if I have breast cancer?

It's unusual for teenagers to get breast cancer. Lumps, bumps and changes to the breast are common, and most of them are non-cancerous (benign).

There's no set method of checking your breasts, but get to know what they look and feel like so you'll notice any changes. It's normal for your breasts to change in size or become more tender during your menstrual cycle.

When must I have a cervical screening test?

A cervical screening test (formerly called a smear test) is a test where cells are taken from a woman's cervix (located above the vagina) to check for changes that could lead to cervical cancer. Cervical cancer can be prevented if it's detected early through cervical screening.

In England, cervical screening tests are offered to women from age 25 upwards every three to five years. You can request a screening test before this age if you're concerned – talk to your GP.

What is the hymen?

The hymen is a ring of thin skin that covers part of the opening of the vagina. It does not cover the vagina completely. Every girl is born with a hymen, but it can break when using tampons, playing sport or doing other activities, including having sex.

Do you put on weight when you're on the Pill?

No, there's no evidence the contraceptive pill causes weight gain. Some girls and women put on weight while they're taking the Pill, but so do girls and women who aren't taking it.

If you've got any questions about the Pill or any other methods of contraception, such as the injection, implant or patch, go to a GP, local contraceptive clinic or young person's service – call the national sexual health helpline on 0300 123 7123. You can get free and confidential advice about sex, contraception and abortion even if you're under 16.

Find sexual health services near you.

Can you get pregnant if you have sex during your period?

Yes. A girl can get pregnant if she has sex with a boy at any time during her menstrual cycle, and can get pregnant the first time she has sex.

That's why you should always use contraception. There are lots of different methods, including:

• combined pill
• condoms
• contraceptive cap
• contraceptive implant
• contraceptive injection
• contraceptive patch
• diaphragms
• female condoms
• intrauterine device (IUD)
• Mirena (intrauterine system or IUS)
• natural family planning
• progestogen-only pill (mini-pill)
• vaginal ring

Only condoms help to protect you against STIs and pregnancy, so use condoms as well as your chosen method of contraception every time you have sex.

What is the clitoris?

The clitoris is a small, soft bump in front of the entrance to the vagina. It's very sensitive, and touching and stimulating it can give strong feelings of sexual pleasure. This is how most girls masturbate. Most girls and women need the clitoris to be stimulated to have an orgasm during sex.

Find out 15 things you should know about sex.

Underweight teen boys

Are you worried about being underweight? Or perhaps your friends or parents have mentioned it?

We all grow and develop at different rates. You may have friends who are taller, heavier and more muscular than you. Lots of boys don't reach their adult height and weight until they are over 18.

You can check whether you're a healthy weight by using our healthy weight calculator.

If you are underweight, your GP, practice nurse or school nurse can give you help and advice.

Why are you underweight?

There may be an underlying medical cause for your low weight that needs to be checked out. Gut problems like coeliac disease, for example, can make people lose weight.

Read about other medical problems that can cause unexplained weight loss.

Maybe you're having mental or emotional problems that have affected your eating habits. Depression and anxiety, for example, can both make you lose weight.

Or perhaps you haven't been eating a healthy, balanced diet.

Whatever the reason, if you're concerned about your weight or your diet, the best thing to do is tell someone you trust, such as a parent, your school nurse or GP. There's a lot that can be done to help.

Why being a healthy weight matters

Being underweight can leave you with low energy and affect your immune system. This means you could pick up colds and other infections more easily.

If your diet is poor, you may also be missing out on vitamins and minerals you need to grow and develop.

The good news is that, with a little help, you can gradually gain weight until you get to a weight that's healthy for your height and age.

Healthy diet for teen boys

It's important that you gain weight in a healthy way. Try not to go for chocolate, cakes, fizzy drinks and other foods high in fat or sugar.

Eating these types of foods too often is likely to increase your body fat, rather than building strong bones and muscles.

Ideally you should:

• Base your meals on potatoes, bread, rice, pasta or other starchy carbohydrates, choosing wholegrain versions where possible
• Have some dairy or dairy alternatives, such as soya drinks
• Eat some beans, pulses, fish, eggs, meat and other proteins including two portions of fish every week, one of which should be oily, such as salmon or mackerel
• Choose unsaturated oils and spreads, such as sunflower, rapeseed or olive, and eat them in small amounts
• Drink 6-8 cups or glasses of fluid a day

We all need some fat in our diet, but it's important to keep an eye on the amount and type of fat we're eating.

Try to cut down on the amount of saturated fat you eat – that's the fat found in foods such as sausages, salami, pies, hard cheese, cream, butter, cakes and biscuits.

Cut down on sugary foods, such as chocolate, sweets, cakes, biscuits and sugary soft drinks.

See more healthy eating tips for teenagers.

Strength training can also help to build strong muscles and bones. Find out how to increase your strength and flexibility.

How to boost your calories

Aim to eat three meals and three snacks a day to bump up your energy intake in a healthy way.

Make time for breakfast. Try porridge made with milk and sprinkle some chopped fruit or raisins on top. Have whole milk until you build your weight back up.

Or how about eggs on toast with some grilled tomatoes or mushrooms?

A jacket potato with baked beans or tuna on top makes a healthy lunch and contains both energy-rich carbohydrates and protein. Adding cheese will provide calcium. Or try pasta salad with chicken breast and tomatoes.

Have a healthy snack before bed. Lower-sugar cereal with milk is a good choice, or some toast. Go for wholemeal where possible.

See Change4Life for more healthy meal ideas.

Find out how many calories the average teenager needs.

Ideas for healthy snacks

Aim for three snacks a day to bump up your calorie intake. Try:

• Crumpets, bananas or unsalted nuts
• Hummus with pitta bread, carrots sticks or celery sticks
• Beans or eggs on wholemeal toast
• Toast with lower-sugar lower-salt peanut butter
• Fruit teacake, hot cross bun, malt loaf or fruit bread
• Wholemeal bagel and lower-fat cream cheese

See Change4Life for more healthy snack ideas.

You should also make sure you get plenty of sleep. About 8 to 10 hours a day is ideal for teenagers.

Avoid smoking and alcohol.

Teen boys and eating disorders

If you feel anxious when you think about food, or you feel you may be using control over food to help you cope with stress, low self-esteem or a difficult time at home or school, then you may have an eating disorder.

If you feel you may have an eating disorder tell someone, ideally your parents, guardians or another adult you trust.

The eating disorders charity b-eat has a Youthline, where you can get confidential advice.

Periods and fertility in the menstrual cycle

The length of the menstrual cycle varies from woman to woman, but the average is to have periods every 28 days. Regular cycles that are longer or shorter than this, from 21 to 40 days, are normal.

"The menstrual cycle is the time from the first day of a woman's period to the day before her next period," says Toni Belfield, a specialist in sexual health information, and a trained fertility awareness teacher.

"Girls can start their periods anywhere from age 10 upwards, but the average is around 12 years," says Belfield. "The average age for the menopause (when periods stop) in this country is 50-55."

Between the ages of 12 and 52, a woman will have around 480 periods, or fewer if she has any pregnancies.

Read more about starting periods.

What happens during the menstrual cycle?

To understand the menstrual cycle, it helps to know about the reproductive organs inside a woman's body. These are:

• two ovaries – where eggs are stored, developed and released
• the womb (uterus) – where a fertilised egg implants and a baby develops
• the fallopian tubes – two thin tubes that connect the ovaries to the womb
• the cervix – the entrance to the womb from the vagina
• the vagina

The menstrual cycle is controlled by hormones. In each cycle, rising levels of the hormone oestrogen cause the ovary to develop and release an egg (ovulation). The womb lining also starts to thicken.

In the second half of the cycle, progesterone helps the womb to prepare for implantation of a developing embryo.

The egg travels down the fallopian tubes. If pregnancy doesn't occur, the egg is reabsorbed into the body. Levels of oestrogen and progesterone fall, and the womb lining comes away and leaves the body as a period (the menstrual flow).

The time from the release of an egg to the start of a period is around 10-16 days. Watch an animation about how the menstrual cycle works.

What are periods?

A period is made up of blood and the womb lining. The first day of a woman's period is day one of the menstrual cycle.

"Periods last around two to seven days, and women lose about three to five tablespoons of blood in a period," says Belfield.

Some women bleed more heavily than this, but help is available if heavy periods are a problem.

Find out about treatments for heavy periods.

What happens during ovulation

Ovulation is the release of an egg from the ovaries. A woman is born with all her eggs.

Once she starts her periods, one egg develops and is released during each menstrual cycle. After ovulation, the egg lives for 24 hours.

Pregnancy happens if a man's sperm meet and fertilise the egg. Sperm can survive in the fallopian tubes for up to seven days after sex.

Occasionally, more than one egg is released during ovulation. If more than one egg is fertilised it can lead to a multiple pregnancy, such as twins.

A woman can't get pregnant if ovulation doesn't occur. Some methods of hormonal contraception – such as the combined pill, the contraceptive patch and the contraceptive injection – work by stopping ovulation.

When are you most fertile?

"Theoretically, there's only a short time when women can get pregnant, and that is the time around ovulation," says Belfield.

It's difficult to pinpoint exactly when ovulation happens but in most women, it happens around 10-16 days before the next period.

"It's not accurate to say that women are fertile on day 14 of the menstrual cycle," says Belfield. This might be true for women who have a regular, 28-day cycle, but it won't apply to women whose cycles are shorter or longer.

For more information on fertility awareness, see the FPA guide to natural family planning.

Normal vaginal secretions

Vaginal secretions (sometimes called vaginal discharge) change during the menstrual cycle. Around the time of ovulation, they become thinner and stretchy, a bit like raw egg white.

See your GP if you are concerned about a change in your vaginal discharge.

Read more about getting pregnant, fertility and period problems.

Talking to your teenager

Getting teenagers to talk openly about what's bothering them can be hard. Follow these tips to help get them talking to you about their worries.

1. Ask, don't judge

Start by assuming they have a good reason for doing what they do. Show them you respect their intelligence and are curious about the choices they've made.

If you don't pre-judge their behaviour as "stupid" or "wrong", they're more likely to open up and explain why their actions made sense to them.

2. Ask, don't assume or accuse

Don't assume that you know what's wrong. Rather than asking "Are you being bullied?", try saying "I've been worried about you. You don't seem your usual self, and I wondered what's going on with you at the moment? Is there anything I can help with?".

3. Be clear you want to help

If you suspect your child is using drugs or drinking excessively, be gentle but direct. Ask them, and let them know that you'll help them through any of their difficulties.

4. Be honest yourself

Teenagers will criticise you if you don't follow your own advice. If you drink too much alcohol yourself, for example, they're likely to mention it ("You can't talk!"). Make sure you're acting responsibly yourself.

5. Help them think for themselves

Instead of trying to be the expert on your teenager's life, try to help them think for themselves:

• Discuss the potential implications of poor behaviour choices. For example, "How does smoking dope make you feel the next day? So, if you feel like that, how's that going to affect you playing football?"
• Help them think critically about what they see and hear. "So Paul said X: is that what you think?"
• Help them feel that they can deal with life's challenges. Remind them of what they're good at and what you like about them. This will give them confidence in other areas of their lives.
• Information is empowering. Point them towards websites that can give them information on drugs, sex and smoking so they can read the facts and make up their own minds.
• Help them think of ways they can respond and cope. "So, when you feel like that, is there anything you can do to make yourself feel better?"
• Encourage them to think through the pros and cons of their behaviour.

6. Pick your battles

If they only ever hear nagging from you, they'll stop listening. Overlooking minor issues, such as the clothes they wear, may mean you're still talking to each other when you need to negotiate – or stand firm – with them on bigger issues, such as drugs and sex.

7. If they get angry, try not to react

Teenagers often hit out at the people they most love and trust, not because they hate you, but because they feel confused.

Don't think that they mean the bad things they say ("I hate you!"). They may just feel confused, angry, upset, lost or hormonal, and they don't know how to express it.

8. Help them feel safe

Teenagers often worry that telling an adult will just make things worse. You need to be clear that you want to help them and won't do anything they don't want you to.

This may be particularly important with bullying. If your child opens up to you about bullying, explain that it isn't acceptable. Listen to their fears and reassure them it's not their fault.

Help build up their confidence by reassuring them that you'll face the problem together.

9. Avoid asking questions they won't answer

Sometimes you'll find out more about your teenager if you ask open questions. If they have an eating disorder, for example, asking confrontational questions like "What did you eat for lunch?" or "Have you made yourself sick?" may mean you get a dishonest answer.

Sticking to open questions such as "How are you?" or "How has your day been?" helps your teenager talk to you about how they're feeling.