Periods last around two to seven days. The average menstrual cycle lasts 28 days, although it's normal to have a cycle that's shorter or longer.
This page covers:
Missing a period could mean you're pregnant. If you've had sex and miss a period, take a pregnancy test.
If you think you may be pregnant, see your GP. You should also see your GP if you're not pregnant and have missed more than three periods in a row.
The most common reasons for missing a period, other than pregnancy, are:
You should also see a GP if your periods stop before you're 45 or you're still bleeding when you're over 55.
Read more about missed periods.
Bleeding between periods or after sex
There are many different causes of bleeding between periods or after sex. It may not be anything to worry about, but it can be a sign of infection, an abnormal cervix or, in rare cases, cancer.
Bleeding between periods is also common during the first three months of starting hormonal contraception.
If you're worried about your bleeding, see your GP, or visit your local sexual health or genitourinary (GUM) clinic for advice, testing and treatment.
Read more about what causes bleeding between periods.
Sudden period changes
If your periods suddenly change – for example, they become heavier or longer, or you're having erratic bleeding – see a GP. This is especially important for women over 40.
Changes in women over 40 can be associated with endometrial cancer, cervical or endometrial polyps, or a pre-cancerous condition (hyperplasia), which can be treated if caught early.
For most women under 40, slightly irregular cycles are usually nothing to worry about, but see your GP if you're concerned about any changes.
Bleeding after the menopause
Postmenopausal bleeding is vaginal bleeding that happens at least 12 months after your periods have stopped.
Although it's a common problem, it's not normal to bleed at this time – even if it's just spotting. Make an appointment to see your GP as soon as possible.
Read one woman's experience of bleeding after the menopause.
Bleeding while taking HRT
If you're taking HRT to control the symptoms of menopause, this can sometimes cause bleeding or spotting, depending on the type of HRT you are taking.
If you take the cyclical (sequential) preparation, then you'll have a regular period-type bleed, known as a withdrawal bleed. See a GP if you notice any bleeding between your withdrawal bleeds, whether it happens after sex or at any other time.
If you take the continuous combined preparation, you won't have a regular bleed, but you may notice spotting. See a GP if this spotting becomes persistent or heavier than just spotting.
If you switch from cyclical to continuous combined HRT and you notice bleeding, stop taking it and seek medical advice.
Find out about self-help methods for coping with the menopause.
Discharge during your period
It's normal to have vaginal discharge (secretions), and for the texture and amount of discharge to vary throughout your menstrual cycle.
See a GP if you have discharge that smells, or is green or bloodstained, as this could be a sign of infection.
Read more about periods.