The number of girls starting puberty early soared during the pandemic.
Researchers suggested the rise could be due to stress or reduced physical activity.
A study looked at 133 girls in Italy who were referred to a specialist paediatric unit because their chests had started to develop before the age of eight.
In the four years before the pandemic, from January 2016 to March 2020, 72 girls were diagnosed with ‘rapidly progressive’ early puberty – which equates to less than two a month.
Symptoms of early puberty could include height increasing too quickly or high levels of hormones linked to adolescence.
But in the period between March 2020 and June 2021, almost four girls a month were being diagnosed – or 61 in total.
Researchers found that during this period when Italy was largely under lockdown, the girls spent an average of two hours a day using electronic devices and 88.5 per cent ceased all physical activity.
There is a significant lack of knowledge about the causes of children going through puberty early but some experts have suggested the blue light from screens and a lack of exercise could disrupt girls’ hormonal development.
Dr Mohamad Maghnie, who led the study from the University of Genoa and the Giannina Gaslini Institute, said: “The role of stress, social isolation… and the increased use of hand and surface sanitisers represent potentially further interesting hypotheses as to why early puberty is increasing in youth.”
Children generally enter puberty earlier nowadays because rates of obesity are higher and carrying too much fat can disrupt the hormones that determine when a child becomes a teenager.
But the study, published in the Journal of the Endocrine Society, found no significant difference in the weight of girls who were diagnosed as going through puberty early before Covid and those who went through it during the pandemic.
There is also a chance that, during lockdown, girls’ parents were more likely to notice early signs of puberty, leading to earlier diagnoses.