Risk factors for childhood overweight in 6- To 7-y-old Hong Kong children

OBJECTIVE: To identify risk factors for overweight in Hong Kong children aged 6-7 y. DESIGN: Case-control study. SETTING: Student Health Service Centres, Hong Kong. SUBJECTS: A total of 343 Hong Kong Chinese children aged 6-7 y old categorised into three groups, an overweight group (≥ 92nd centile for BMI), a normal middle-weight group (45th-55th centile for BMI) and a normal low-weight group (≤ 8th centile for BMI). MEASUREMENTS: Subjects and their parents/caregivers were interviewed at home. Data on lifestyle habits, dietary habits, family structure and demographic background were collected by questionnaire. A 3-day dietary record was administrated by the parents/caregivers to assess dietary intake of the children. RESULTS: Logistic regression analyses (overweight group compared with middle-weight plus low-weight groups) showed that childhood overweight was significantly associated with parental obesity (BMI ≥ 25 kg/m², Asian reference) (paternal: OR = 2.66, 95% CI = 1.51-4.70; maternal: 5.07, 2.62-9.79) but not parental overweight (BMI = 23-25 kg/m²). After adjustment for parental obesity, the odds ratio for childhood overweight was increased by birth weight (< 3.0 kg as reference, 3.0-3.5 kg: 2.13, 1.18-3.84; ≥ 3.5 kg: 4.89, 2.49-9.60) and decreased by sleeping duration (< 9 h/day as reference, 9-11 h/day: 0.54, 0.30-0.97; ≥ 11 h/day: 0.31, 0.11-0.87). Childhood overweight was also significantly associated with higher energy consumption (2.62, 1.20-5.74) and having a father who was a current smoker (2.08, 1.25-3.46). CONCLUSIONS: Although healthy diet and regular exercise will remain the cornerstones of obesity management in children, our data support the view that education about maintaining a healthy weight could be introduced much earlier in those families with high-risk children, as indicated by high parental BMI or high birth weight. The utility and practicality of such an approach should be carefully evaluated before becoming part of any public health policy. Further study of the role of short sleeping duration and parental smoking on childhood obesity development is warranted.