Research findings, published in Nature give clues to why early puberty may be linked to an increased risk of health conditions. "Menarche is associated with the development of health conditions later in life in women such as diabetes, cardiovascular disease, and breast cancer," said Dr Joanne Murabito, Associate Professor of Medicine at Boston University School of Medicine. Scientists at 166 institutions analysed the DNA of more than 180,000 women in one of the largest studies of its kind. The timing of when a girl reaches puberty is controlled by hundreds of genes, say scientists.

Most girls start their periods between the ages of 10 and 15, with an average age of 12-13. Researchers found that hundreds of genes were involved in the timing of puberty. While genes play a role in timing, environmental factors are also important. Factors such as childhood body mass index (BMI) and exercise have also been linked to puberty.

The researchers say the age a woman has her first period is associated with the risk of chronic diseases. "By studying genetic factors we hope to better understand how puberty timing in girls is linked to important health conditions in women."

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