Research Report: Early Puberty in 11-year-old Girls: Millennium Cohort Study Findings
Charlotte Goddard
Tuesday, November 8, 2016
Researchers examine whether, and how, a girl's social and economic circumstances and her ethnicity might be linked to the early onset of puberty.
Authors Yvonne Kelly, Afshin Zilanawala, Amanda Sacker, Robert Hiatt, Russell Viner
Published by Archive of Diseases in Childhood, September 2016
SUMMARY
In the UK, the median age for girls to start their periods is 12 years and nearly 11 months. Early puberty in girls is associated with a number of adverse outcomes throughout their life, including the increased risk of early sexual activity and teenage pregnancy, poor mental health in adolescence, mid-life cardiovascular disease and breast cancer. However, it is also associated with better bone health in early old age. Past research has found links between early puberty and factors such as obesity, stress, pollutants, migration and genetic factors.
Researchers from University College London wanted to find out whether, and how, a girl's social and economic circumstances and her ethnicity might be linked to the early onset of puberty. Their research was funded by the Economic and Social Research Council. They examined information from 5,839 girls who participated in the Millennium Cohort Study, which has been tracking the lives of 19,000 UK children born in 2000 to 2001. The first set of data was collected when participants were around nine months old and the subsequent four sweeps of data were collected at three, five, seven and 11.
The researchers found one in 10 girls were starting their period by the time they were 11 years old. On average, girls who were heavier at age seven and suffered stress in early childhood were more likely to have begun menstruating by age 11.
The team found 9.5 per cent of their sample of 11-year-old girls had started their periods. A greater percentage of girls in the poorest group had started menstruating - 14.1 per cent - compared with 6.8 per cent in the wealthiest group. Indian, Bangladeshi and Black African girls were most likely to have begun menstruation - 24.2 per cent, 21.6 per cent and 20.1 per cent respectively.
Affluence was found to be the greatest indicator of when puberty would start with girls in the poorest income group more than twice as likely and those in the second poorest group nearly twice as likely to have begun menstruation, compared with girls in the richest income group.
When the research findings were adjusted to take other factors into account, it was apparent differences in income, excess body weight and stress accounted for part or all of the differences between ethnic groups in most cases. The researchers found girls from less wealthy backgrounds were more likely to have a higher BMI (body mass index) and their mothers were more likely to experience psychological distress, all of which appear to be an indicator of beginning menstruation earlier in life.
Material disadvantage and obesity were associated, to varying degrees, with early puberty in girls from Pakistani, Bangladeshi and Black African backgrounds. However, the researchers could not explain the likelihood of Indian girls, who tended to come from more affluent backgrounds than their white peers, to start their periods earlier.
IMPLICATIONS FOR PRACTICE
There are clear socio-economic and ethnic inequalities in health in later life. Early puberty could play a role in increasing the risk of chronic disease among women from disadvantaged groups, suggest the researchers. Improving understanding of the processes could help identify opportunities for beneficial interventions throughout a woman's life.
FURTHER READING
Early Puberty and Adolescent Pregnancy: The Influence of Alcohol Use, Julianna Deardorff and others, Pediatrics, December 2005. Examines the role alcohol plays in the timing of sexual intercourse and pregnancy among early-maturing young women.
Association Between Pubertal Development and Depressive Symptoms in Girls from a UK Cohort, Carol Joinson and others, Psychological Medicine, December 2012. A study of 2,506 girls from the Avon Longitudinal Study of Parents and Children which found depressive symptoms in mid-adolescence were more strongly influenced by breast stage than when girls started their periods.
Earlier Onset of Puberty in Girls: Relation to Increased Body Mass Index and Race, Paul Kaplowitz and others, Pediatrics, August 2001. A study of whether earlier onset of puberty could be attributable to the increasing prevalence of obesity in young girls.