As a young girl, getting your period for the first time is a big deal. It comes with mental and social expectations around “becoming a woman” and a host of cultural practices that act to celebrate or stigmatise menstruation. 
But now suggests the timing of this event could also have health implications for girls who get their first period earlier than their peers.
During puberty our bodies change and sexually mature, and a girl’s first period is an important point in this process. The age when girls get their first period varies, however younger than 12 years is generally considered to be “early”. The possibility that a first period before the age of 12 is linked with pregnancy health was explored in our . We found that girls who had early first periods were more likely to develop diabetes when they later became pregnant as an adult.
Gestational diabetes is a , as it increases the risk of pre-term labour and giving birth to a large baby. It is also considered a “stress test” for the later development of type 2 diabetes; both the and in affected pregnancies face a six to seven fold increased risk of developing type 2 diabetes.
Gestational diabetes increases the risk of both mother and child going on develop type two diabetes. (Flickr/ Frank de Kleine/ CC BY 2.0) Source: Flickr/ Frank de Kleine/ CC BY 2.0
Age of first period and diabetes during pregnancy
We studied a group of more than 4,700 women from the (also known as Women’s Health Australia). This longitudinal study has collected detailed health and well-being information from the same women at multiple points in time over the past 20 years. The women were 18-23 years old in 1996 when the study started. The women reported on the age of their first period and were followed throughout their pregnancies.
Most women experienced their first period between age 12 and 13, but 12% had early first periods. We found girls who had their first periods before age 12 were more likely to be from a disadvantaged background in childhood. They were also more likely to report being overweight in childhood and in adult life, compared with women who had their first period at a later age. While taking these early life and adulthood characteristics into account, women with earlier first periods were still .
Is the age at first period changing?
The age of first menstruation has decreased in most Western countries, from an . This decline seems to have , however discussion persists about whether the trend is continuing at a slower rate. The initial decline is likely explained by improved health and nutrition. The more recent declines may also be largely attributable to environmental and lifestyle factors.
We know circumstances in early life – including , such as parental divorce and abuse, as well as – can trigger early reproductive development. Other – such as the use of hair products, plastic water bottles, and food packaging – have also been examined as a possible cause of .
What does this mean for women’s health?
An early transition to adulthood can be characterised by increased stresses and challenges as girls have to adapt to their new social roles. Girls with an early first period are at greater risk of , and display higher rates of risky-behaviours such as , and .
The falling age of first menstruation is concerning as it also increases the risk of health conditions. In addition to the higher risk of found in our study, early menstruation has also been shown to increase the risk of developing chronic conditions in later life, such as and .
What can we do?
Ideally we would one day be able to prevent girls from having their first period too early, but there is no one single cause that determines when this happens. However, supporting healthy environments and behaviours from early in life are important strategies. Childhood obesity is a well-known factor increasing the likelihood of early age at first period. Given that , promoting healthy eating and physical activity should be a priority for young mothers, schools, and health policy.
Clinicians including GPs and specialists, who provide advice and treatment for women, should be aware of the importance of early age at first menstruation as a potential marker of future health issues. Early monitoring and advice on a healthy diet and weight and physical activity may help women to lower these risks.
, PhD Candidate and Research Officer, and , Professor of Life Course Epidemiology, Faculty of Medicine,
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