AKA: blobbing, coming on, menstruation, monthlies, on the blob, on the rag, the curse, time of the month, surfing the crimson wave.
What are periods?
When your body has developed enough to have a baby, your ovaries will release an egg each month. This is called ovulating. Meanwhile, a thick lining will form in your womb so a baby could grow.
If the egg isn’t fertlised by sperm (i.e. it doesn’t start developing into a baby) it will be discarded, along with the womb lining, through the vagina. This is a period - it usually lasts from three to eight days.
These monthly changes - from the start of your period to the start of the next - is your menstrual cycle. It usually takes about 28 days to go full circle.
When will I start?
The average age is 13, but it could be any age from 8 to 20. Signs your periods may start soon are breast growth, finding discharge in your knickers and pain in your stomach or lower back.
What should I do when I start?
Most girls’ periods are irregular at first, so don’t expect them like clockwork every 28 days. Still, it’s worth making a note of when they happen, so you’ll know when they’re settling down and be prepared each month.
You’ll need sanitary protection to soak up your period, like tampons, or sanitary towels (STs). It’s best to try different kinds to find what’s best for you, but most girls start using STs.
Do periods hurt?
Most girls get mild stomach or back ache, for others it can be a lot worse.
Exercise is the best cure, or resting a hot water bottle where it hurts, taking a hot bath, lying down and breathing deeply, or taking painkillers. If you regularly have really bad pains, your doctor may be able to give you some stronger pills.
Some girls get pre-menstural syndrome (PMS) just before their periods, which usually means mood swings or mild depression and can be reduced by a healthy diet and exercise.
Want to know more about what's going on throughout your cycle? Read our day-by-day guide to your period.
Further help and advice
• bbc.co.uk/science
• likeitis.org.uk
Disclaimer: the BBC can't be held responsible for the content of external websites.
Pictures posed by models.
