A period is a bleed from the uterus (womb) that is released through the vagina. It happens approximately every 28 days, although anywhere between 24 and 35 days is common. A period is part of a woman's menstrual cycle.

Periods can begin between the ages of eight and 16 years, but they usually start around the age of 12. They continue every month until the menopause, which usually occurs between 45 and 55 years of age. 

What is menorrhagia? 

Menorrhagia is the medical name for heavy periods. The amount of blood that is lost during a woman's period varies from person to person, with some women experiencing more blood loss than others. Menorrhagia can occur by itself or in combination with other symptoms, such as menstrual pain (dysmenorrhoea).

Menorrhagia is defined as excessive (heavy) bleeding that occurs over several consecutive menstrual cycles. Heavy bleeding does not necessarily mean that there is anything seriously wrong, but it can affect a woman physically, emotionally and socially, and can cause disruption to everyday life. 

How much is heavy bleeding? 

The amount of blood that is lost during a woman's period can vary considerably for each woman, so it is difficult to define exactly what a heavy period is.

In research, heavy menstrual bleeding is considered to be 60-80ml (millilitres) or more per cycle (the average amount of blood lost is 30-40ml, and 90% of women lose less than 80ml). However, in reality, it is difficult to quantify objectively what heavy blood loss is, and most women have a good idea about how much bleeding is normal for them during their period, and can tell when this amount increases or decreases.

If your periods are causing disruption to your everyday life, or they are heavier than usual, you should speak to your GP about it. If you feel that you are using an unusually high number of tampons or pads, experience flooding through to your clothes or bedding, or you need to use tampons and towels together, it is a good indication that your blood loss is excessive.