A sign that your body is preparing for the time when you might one day have a baby, a period (also known as menstruation) usually happens once a month. During puberty, the hormones (chemical messengers) progesterone and oestrogen are released by the brain and these ‘tell’ your ovaries and eggs to start growing and your periods will start. Periods usually start around the age of 12 (between the ages of 9 and 15) and stop at around age 45 to 55, when women go through the menopause.
Once every 28 days, or thereabouts (see below), your ovaries will release an egg (known as ‘ovulation’). It travels along your fallopian tube to your uterus where the egg can be fertilised by a sperm after unprotected intercourse, starting the development into a baby. The egg will not be fertilised if you are not having sexual intercourse (or if you are having intercourse but use contraception).
The unfertilised egg breaks down in the uterus where the unwanted soft lining also breaks down and these dissolve together and pass out through the vagina. About a couple of tablespoons of blood and tissue dribble out over the course of a few days, so it is quite a small amount. This is what’s known as your period. Your periods will stop if you become pregnant (no eggs are released while a baby is growing in your uterus) and while the baby is breastfed.
When will it start?
Your period can happen at any time – at home, when you’re at school, when you’re out and about – so it is a good idea to carry a pad with you in your bag just in case. These often come neatly wrapped so you can tuck one discreetly in a pocket. If you don’t have anything with you, you can roll up some toilet paper and pop that in your knickers until you can find a pad. Don’t worry – your first period is usually a very tiny amount of blood and discharge. Once you are having periods regularly, you will know when they are likely to start and will be prepared. The average period lasts for about 3 to 8 days.
Periods at school
You might worry about managing your period when you’re at school (changing your pad or tampon, possible leakage and being discreet) but do remember that all girls are in the same boat. If you’re caught short, the chances are one of your friends will be prepared. Your school should have special bins in the toilets for disposing used tampons and pads (which should never be flushed down the toilet) and there should be soap and paper towels or a hand dryer for you to wash your hands. If there aren’t, speak to someone in your school office.
The time from the start of one period and the start of the next one is roughly about 28 days and is known as the ‘menstrual cycle’. Cycles vary from person to person – some women have cycles of 21 days and others of 35 days. All of this is very normal. Your periods will probably be irregular at first and be irregular for a while. It can take a couple of years before your body settles into a regular cycle. Keep a note of the first day of each period on a calendar so you can work out when your next one should be and ensure you’re not caught off-guard.
If your periods don’t settle into a regular schedule after a couple of years, make an appointment with your GP to check everything is ok. If your periods have been in a regular cycle but they stop for longer than 3 months, you should also consult your GP. If there is any chance you could be pregnant, you need to see a health professional straight away.