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Periods and the menstrual cycle

The menstrual cycle is something a female body goes through each month to get ready for a possible pregnancy.

There are different stages to the menstrual cycle. One stage is menstruation, which is what most people call periods.

If you want to have sex but you don’t want to have a baby it’s important to understand the menstrual cycle so you can understand how some types of contraception (birth control) work. If you want to have a baby, understanding the menstrual cycle can increase your chance of getting pregnant.

What are periods and why do we get them?

A period is when a woman bleeds from her vagina for a few days each month.

Periods are part of the menstrual cycle, which happens to prepare the body for pregnancy. Each month your ovary releases an egg. If that egg remains unfertilised (is not met by a sperm) the lining that was growing in the womb (uterus) to house a fertilised egg will leave the body – this is what a period is.

Women lose around 5 to 12 teaspoons of blood during each period. This might sound like a lot but it’s completely normal!

What age do periods start?

When the body is ready. Most girls start their periods when they are about 12, but they can start as young as 8 or as old as 16.

When a woman reaches the age of 45‒55, her periods will gradually stop. This phase is called menopause.

What are the stages of the menstrual cycle?

The timings for each stage will vary from person to person.

Day 1-5: Period. The first day of the cycle starts on the first day of a woman's period.

Days 5-14: When a period finishes, the womb will start to prepare for a fertilised egg. At around day 12-14, a new egg is released from an ovary (there are two ovaries in the body). These are the days when pregnancy is most likely to happen. But pregnancy can happen any time live sperm meets a live egg.

Days 15-24: The egg travels down the fallopian tube to arrive in the womb, and the womb gets ready to receive the egg by growing a thick lining for the egg to be implanted into.


Days 25-28: If the egg has been fertilised, it will implant into the lining and start to grow into a foetus. This means someone is pregnant and their periods will stop for as long as they are pregnant. But if the egg hasn’t been fertilised it will start to break down and so will the lining. The lining will then be ready to leave the body. And the cycle begins again.

If I start my period does it mean I’m ready to have sex?

Starting your period does not mean you are ready to have sex. Only YOU can decide whether you’re ready, and you should base this on what you think and feel. No one should ever pressure you into having sex.

Am I ready for sex?

If I use birth control will my period stop?

Not necessarily. But you may experience changes in your cycle when you start or stop using some types of contraceptives, such as:

Contraceptive options

When in the menstrual cycle can I get pregnant?

If you don’t use contraception you can get pregnant at any time during your menstrual cycle, even during or just after your period.

You have the highest chance of getting pregnant (called being ‘fertile’) on the day your ovary releases an egg (called ovulation) and the days around it. If a live egg meets live sperm a pregnancy will happen. Your egg lives for about one day after ovulation, and sperm can live in your uterus (womb) and fallopian tubes for up to seven days after sex.

Some people have very regular cycles, but other people don’t. When you first start your periods they are likely to be irregular. This can make it hard to predict when your period will arrive and when you are likely to be most fertile.

If you don’t want to get pregnant you need to use contraception (birth control). And remember – only condoms protect against pregnancy and STIs, including HIV.

What if my period is late?

Don’t panic! It is normal for periods to arrive a few days earlier or later than expected.

But if you have had sex and your period is more than a week late it is a good idea to take a pregnancy test. If you don't want to wait until you've missed your period, you should wait at least one to two weeks after you had sex.

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Do trans men and non-binary people get periods?

Yes. Anybody with a uterus, vagina, fallopian tubes and ovaries can get a period. But not everybody with these things identifies as a girl or woman. This means transgender men and some non-binary people, gender non-conforming people and queer people can get periods.

Having a period can be difficult if you don’t see yourself as female. It can be a reminder that your body doesn’t match the way you feel about who you are (your gender identity). If you are feeling distressed, speak to a trusted healthcare provider about options for making your periods lighter or stopping them all together.

What is PMS?

Throughout the menstrual cycle, people can experience mood and energy changes, cramps, sore breasts and other symptoms. These things are caused by changing hormone levels in the body, which control the menstrual cycle. All these things are called by the medical name ‘pre-menstrual syndrome’ (PMS) and they are completely normal.

What advice can I give to someone about periods?

It’s important to talk to girls from an early age so they're prepared for their period to start. This can be as young as eight. Boys also need to learn about periods so they understand why they happen, what girls experience, and how periods relate to pregnancy.

Periods are natural and they are nothing to be ashamed of. So do not be embarrassed. If you are struggling to raise the issue, you could try discussing a tampon advert to start the conversation. Or you could simply ask someone what they know about periods and go from there.

It's important to use factual information and clear language, which you can find above.

When someone starts their period it's a sign their body is able to have a baby. So it’s also important to speak to them about pregnancy, contraception, HIV and STIs.

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