Girls from low income families are more likely to have started their period by 11 years old than their more wealthy peers, a new study has found.
Researchers found that girls from poorer families are two-and-a-half times more likely to start their period by the age of 11 than children from wealthier backgrounds.
The study looked at how a girl’s social and economic circumstances and her ethnicity might be linked to the early onset of puberty.
The report, by from the ESRC International Centre for Lifecourse Studies in Society and Health, was completed at a centre based at University College London (UCL).
It examined information from almost 6,000 girls who have participated in the Millennium Cohort Study, which has been tracking the lives of 19,000 UK children born in 2000-01.
It found that 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.
Those who had started their periods early also tended to have mothers with higher stress levels, were from single-parent families and tended to have had some social and emotional difficulties themselves.
Indian, Bangladeshi and black African girls were most likely to have started their period at age 11, with Indian girls three-and-a-half-times more likely than their white counterparts to have done so.
The study authors pointed out that early puberty is linked to numerous health outcomes, including increased risk of poor mental health (in adolescence and throughout life), cardiovascular disease and some cancers.
The average age for UK girls to start their menstrual cycle is 12.9 (12 years, and nearly 11 months).
To identify markers for earlier menstruation, Professor Yvonne Kelly and the team of academics at UCL looked at a number of factors including income, weight, ethnicity, stress and parental situation.
They found that affluence was the largest indicator of whether a girl would start her period younger than others.
“After we took account of factors including their weight and early life stress, girls from the poorest and second poorest groups were still one and a half times more likely to have started their periods early,” Professor Kelly explained.
“And as far as ethnicity was concerned, income, excess body weight and stress accounted for part or all of the differences in most cases.
“The findings can perhaps be explained, as we know that girls from less wealthy backgrounds are more likely to have a higher BMI (body mass index), and their mothers are more likely to experience psychological distress – all of which appear to be an indicator of beginning menstruation earlier in life.”
However she added that it was unclear why Indian girls were found to start their period younger than their white peers.
“As most Indian girls come from more advantaged backgrounds compared to their white peers, the likelihood of them having started their period could not be explained when we took all of the factors measured in our study into account,” she said.
The study, which has been published in the journal Archives of Disease in Childhood, showed that one in 10 girls are starting their period by the age of 11.
Professor Kelly explained that the findings could be vital in terms of improving the health of generations to come.
“Given the short- and long-term implications for early puberty on women’s health and wellbeing, improving our understanding of the processes could help identify opportunities for interventions with benefits right across the lifecourse – not just for the girls in our study, but for future generations,” she said.
While the study focused on menstruation cycles of girls, it also demonstrated “considerable different life experiences” of ethnic minority groups in the UK, the study authors added.
“Indians are relatively advantaged whereas Pakistanis tend to be materially disadvantaged; Bangladeshis and black Africans are materially disadvantaged and tend to have higher BMIs compared with the majority ethnic group,” Professor Kelly said.
“We can say with considerable confidence that socioeconomic and ethnic disparities are indeed apparent in the UK.”