Fewer school-age children in Europe and North America smoke or drink alcohol, while many girls believe they are too fat, according to a survey of almost a quarter of a million children.
The report, published on Tuesday, was based on school-based surveys in 42 countries conducted 2013-14, the Copenhagen-based European office of the World Health Organisation said.
Compared with a similar survey 2009-10, the "proportion of 15-year-olds who first smoked at age 13 or younger ... has fallen from 24 per cent to 17 per cent," the report said.
The findings showed that boys were more likely to drink alcohol compared to girls in most countries, but gender differences were small. Weekly drinking dropped from 21 to 13 per cent for 15-year-olds, compared to 2009-10.
The report also raised concerns that most 11-year-olds and older children exercised too little, and that girls more often reported "poorer mental health" than boys. In addition, more girls than boys thought they were too fat, even though boys had a higher rate of obesity.
"The proportion of girls who think they are too fat increases from 26 per cent at age 11 to 43 per cent at age 15. One quarter of 15-year-old girls are on a diet or doing something else to lose weight," said Jo Inchley, international co-ordinator of the report.
A consistent trend was that children skipped breakfast as they grew older, especially girls. Only half of 15-year-old girls said they had breakfast every school day.
There was also a drop in reported sexual intercourse, dipping from 29 per cent to 24 per cent among boys aged 15 and from 23 to 17 per cent among girls of the same age. Two-thirds said they or their partner used a condom when they last had intercourse.
The report, Growing up Unequal, covered three age groups: 11-, 13- and 15-year-olds.
In addition to gender, it factored how health was affected by social relations with family and friends, as well as by family wealth.
Governments can use the findings to develop plans to "promote and nurture the positive health behaviours in childhood and adolescence that lay the foundations for healthy adulthoods," said Zsuzsanna Jakab, head of the WHO European office in Copenhagen.
Compared to the previous survey, soft drink consumption fell among most groups, but one fifth of 15-year-old boys drank soft drinks daily. Soft drinks are linked to weight increase and dental health issues due to the sugar content.
Health complaints - for instance suffering a stomach ache or feeling low or nervous - increased with age. Half of the 15-year-old girls and one-quarter of the boys in that age group experienced multiple health complaints more than once a week.
A trend that might increase in future was cyber bullying due to the growing use of mobile devices, but the current rate was less prevalent than other forms of bullying, the report stated.
