Early menstruation may increase the risk of premature menopause, a new study has found.

According to the findings, girls who get their first period at the age of 11 or under are more likely to undergo early or premature menopause as adults. This risk is increased even more if they do not have any children.

The international study involved over 51,000 women living in the UK, Scandinavia, Japan and Australia.

It found that those who were 11 or younger at the time of their first period had an 80% increased risk of experiencing a natural menopause before the age of 40 (premature menopause), compared with those who had their first period between the ages of 12 and 13.

They were also 30% more likely to experience a natural menopause between the ages of 40 and 44 (early menopause), compared to those who started menstruating at 12 or 13.

The study also found that women who had never been pregnant or who had never given birth had a two-fold increased risk of undergoing premature menopause and a 30% increased risk of undergoing early menopause.

However, this risk increased even more among women who started menstruating early and had no children. They had a five-fold increased risk of undergoing early or premature menopause compared to those who started menstruating at the age of 12 and went on to have at least two children.

"If the findings from our study were incorporated into clinical guidelines for advising childless women from around the age of 35 years who had their first period aged 11 or younger, clinicians could gain valuable time to prepare these women for the possibility of premature or early menopause.

"In addition, they could consider early strategies for preventing and detecting chronic conditions that are linked to earlier menopause, such as heart disease," commented the study's lead researcher, Prof Gita Mishra, of the University of Queensland in Australia.

The researchers noted that most of the women who took part were born before 1960 and for many of them, contraception was less available than it is today, treatment for infertility was limited and women tended to begin menstruating at an older age compared to more recent years. As a result, the researchers warned that these findings need to be interpreted with caution.

However, they believe that the ‘underlying relationship between these reproductive characteristics across life is still present'.

They suggested a range of factors that may influence menstruation and menopause, including genetics, obesity and social environment.

"The message for everyone to take on board from this and other similar studies is to think of the timing of menopause as a biological marker of reproductive ageing, which has implications for health and the risk of chronic diseases.

"So if we want to improve health outcomes in the later life, we need to be thinking about the risk factors through the whole of a woman's life from the early years and the time of their first period through to their childbearing years and menopause," Prof Mishra said.

Details of these findings are published in the journal, Human Reproduction.