Very slim women are much more likely to experience an early menopause, research has found.
Those who are underweight have a 30 percent higher chance risk of hitting the menopause before they are 45.
The study of 80,000 women also found that the risk trebled if they were underweight and lost one and a half stone on three separate occasions.
One theory is that slim women have lower levels of the sex hormone estrogen, which is produced by fat tissue.
Researchers from the University of Massachusetts, in Boston, looked at 78,759 women aged 25 to 42. They found very slim women had a 30 percent higher risk of early menopause
Estrogen levels typically fall in women in their late 40s and early 50s and this is what causes the menopause.
If they are already very low however, the menopause will occur at an earlier age.
Today’s study is further evidence of how women who are very slim are just as likely to experience fertility issues as those who are overweight.
Researchers from the University of Massachusetts, in Boston, looked at 78,759 women aged 25 to 42.
Underweight was classified as having a BMI of less than 18.5 – which is equivalent to being 5ft 5in tall and weighing 8 stone or less.
Women who had been underweight at any age had a 30 percent higher risk of early menopause compared to those of normal weights.
By contrast, women who were overweight – with a BMI of between 25 to 30 – had a 30 percent lower odds of hitting the menopause early.
And underweight women who had lost 20lbs – 9 kilos – on three separate occasions between the ages of 18 to 30 had a 2.4 times higher risk.
The study, published in the journal Human Reproduction, said there were ‘important implications’ for underweight women and their fertility may start to decline earlier than expected.
Dr Kathleen Szegda, the lead researcher said: ‘Our findings suggest that women who are underweight in early or mid-adulthood may be at increased risk for early menopause.
‘Up to 10 percent of women experience early menopause and it is associated with a higher risk of cardiovascular disease, and other health conditions such as cognitive decline, osteoporosis and premature death, so these findings have important implications for women and their doctors.
‘Underweight women may want to consider discussing the potential implications of these findings with their doctors.
‘Causes of early menopause are not clearly understood. Our findings suggest that being underweight may have an impact on the timing of menopause. More research is needed to understand how it increases the risk of early menopause.’
The menopause normally occurs between the ages of 45 to 55 and in the UK, the average age is 51.
But one in ten experience it before the age of 45 and one in 100 before the age of 40 – and often there is no obvious cause.