Hong Kong children have grown taller and heavier, probably due to better nutrition and improved socioeconomic factors: study
- Median height for 18-year-olds of both sexes up by about 2cm, with weight increases also recorded
- Research figures will be used to revise height and weight charts for children last updated in 1993
Researchers from the Chinese University of Hong Kong, the University of Hong Kong, and the Department of Health on Monday also revealed a new growth chart to track the physical development of youngsters based on their findings and which would be introduced in public hospitals by the end of the year.
“When it comes to height and weight, contemporary children are heavier and taller than [before],” Dr Thomas Chung Wai-hung, a consultant in community medicine at the Department of Health, said.
“Having analysed the data we have collected … it is our opinion that the 1993 charts are no longer appropriate for monitoring the growth trend of Hong Kong children.”
It found that the median height of 18-year-olds of both sexes had increased by about 2cm (0.8 inches) by 2020 compared with 1993, when the healthcare sector’s growth charts were last updated.
The median height for boys was up to 172.5cm, from 170.9cm, and girls stood at 160.2cm, up from 158.2cm.
Researchers also found that children were generally heavier, but said it was harder to provide exact figures on the change because of variances in age and growth factors.
Tony Nelson, a professor at Chinese University’s department of paediatrics, who helped present the findings on Monday, said that the findings suggested a “secular trend” that had been seen in other countries around the world.
“It’s presumed to be [that] improving nutrition, lifestyle and other social factors over decades will result in this increase in height,” he added.
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Hong Kong infants up to two years of age, however, were lighter compared with the World Health Organization’s (WHO) 2006 child growth standards.
Girls between the ages three to five years were also shorter than other populations studied by the WHO.
But Nelson said that showed the “importance of local data,” as the WHO study looked at statistics from many countries, including the United States and India.
“This just reflects the genetics of the local population here,” he said. “It’s all quite normal.”
The researchers used the information gathered, as well as figures from similar studies elsewhere, to create a new set of growth charts, which will start to be used in the Department of Health’s Maternal and Child Health Centres from July.
The Hospital Authority will also introduce the new charts in phases from September, with the revised standards expected to be in use in all locations by the end of the year.
The new charts will cover weight, height, body mass index (BMI) and head circumference for smaller children.
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Under the new guidelines, the previous weight-for-height chart will be replaced with a new BMI-for-age chart, which the researchers said would cut the number of children of normal weight being miscategorised as overweight or obese.
Healthcare staff will also be able to use the WHO’s 2006 guidelines for children aged under five, in particular for children of non-Chinese ethnicity when it was considered appropriate, they added.
The number of centile lines – used to define ranges for weight and height – will also be increased from seven to nine, with the two additional lines denoting new extremes at either end at 99.6th and 0.4th centile respectively.
The new standard will also be included in a new version of the Child Health Record, which the Department of Health is updating.
Chung said that parents should not be concerned too much about which centile their child’s growth pattern fell under, as it depended on a variety of factors, including sex, ethnicity, the height of their parents and other hereditary factors.
“If the child is at the 25th or 75th centile lines, and they are growing along the line and there are no other clinical issues, then parents shouldn’t have to be worried,” he added.
