What is a normal period? For some its a heavy bleed for two days that gradually gets lighter, for others its a light flow that eventually dries up and for some it's a blink and you'll miss it kind of bleed, ranging from 3 – 7 days.

But one things for sure, it's something that at some point all women have experienced and as much as it is a regular cycle for them it can differ from month to month.

And a recent study has confirmed this and revealed that when it comes to menstruation no two periods are the same.

Experts at University College London and contraceptive app Natural Cycles conducted one of the biggest menstrual cycles to date.

What is a normal cycle?
What is a normal cycle?

The study analysed data from over 600,00 menstrual cycles was last month published in Nature Digital Medicine and analysed data 124,648 women from Sweden, USA and the UK.

"The studies confirmed that women are totally individual", said Professor Joyce Harper, head of Research Department of Reproductive Health at UCL.

"There is a huge variability when it comes to women and their menstrual cycles from the days they bled, overall length and the day they ovulate. She aded "it's clear to see the value in gaining an understanding of what is normal for each individual when it comes to their own bodies – so they can spot when something is off". So ladies make sure you keep a check on your dates and take note if your period differs month to month, if there is drastic change in your cycle; it may be unusually heavy or barely there, consult your doctor straight away.

The research found that the shorter the cycle (characterised by 21 days or less ) the shorter the bleed, or ‘very long cycles (35 days or above) has a longer bleed.

Natural Cycles and UCL’S research found that only 13% of the women they assessed had cycles that lasted 28 days.

The average cycle length is a little longer than suspected . Explaining how the menstruation cycle works Professor Joyce Harper said that the length of a menstrual cycle is calculated as the number of days between periods. The first day you bleed is day one and it will finish the day before your next period starts.

sanitary pad with rose petals.Pink background

However, while the length of our period differs so greatly among women Natural Cycles research shows one clear pattern amongst most women and that is your period gets shorter the older you get. So it's good news to all you ladies that are unlucky enough to endure a full seven day bleed it does get better and your periods do get lighter.

Head of Medical Affairs at Natural Cycles Dr Simon Rowland explained “We found a difference of 2.9 days between the average cycle length of the youngest and the oldest groups and this is thought to be due to many external factors including stress”.

However, Rowland concluded “more research in this area is needed”. The main thing that has emerged from this study is that women really need to find out what their “normal’ is when it comes to their menstrual cycle and monthly bleed.

Once they have a clear understanding how their cycle works, woman can more easily detect when something looks or feels different. As certain symptoms relating to periods are indicative of varying gynaecological conditions.