Trends in overweight and obesity among rural preschool children in southeast China from 1998 to 2005

Abstract

Objective

To examine the trends in prevalence of overweight and obesity, as well as the impact of stunting on overweight/obesity, among rural children aged <60 months in southeast China between 1998 and 2005.

Study design

Data from the population-based Child Health Care Surveillance System (CHCSS) from eight counties in southeast China were used. Overweight and obesity were defined as weight-for-height/length z score >2 and >3 standard deviations (SDs), respectively, and stunting was defined as height/length-for-age z score <−2 SD, in accordance with the 2006 World Health Organization growth standard.

Methods

A total of 550,693 clinic visit records of 280,931 children from the CHCSS, collected between 1998 and 2005, were included in the analysis. The age- and sex-adjusted prevalence rates of overweight, obesity and stunting were estimated for each year, and the trends over time were examined. The impact of stunting on overweight/obesity was determined using multiple logistic regression analysis.

Results

The prevalence of overweight increased from 3.7% in 1998 to 3.9% in 2005 (P < 0.001), but no increase in the prevalence of obesity was observed (0.5% in 1998 and 0.6% in 2005; P > 0.05). The prevalence of obesity increased significantly in 2005 compared with 1998 among boys aged ≥24 months, but was similar between 1998 and 2005 for girls aged ≥12 months. The prevalence of stunting decreased from 3.9% in 1998 to 1.6% in 2005 (P < 0.001). There was a positive association between stunting and overweight/obesity in both 1998 and 2005, although the association was attenuated in 2005.

Conclusion

There was a small increase in the prevalence of overweight among rural preschool children in southeast China from 1998 to 2005. The prevalence of obesity remained stable. However, the prevalence of stunting decreased and its positive influence on overweight/obesity was weaker in 2005.

Introduction

Overweight and obesity among preschool children is of great concern as it tends to track into adolescence and adulthood, and has long-term negative health consequences.1, 2, 3 In developed countries, studies have shown an increasing rate of overweight/obesity in preschool children.4, 5 Worldwide estimates indicate that the prevalence of overweight and obesity among preschool children rose between 1990 and 2010, not only in developed countries but also in developing countries.⁶

In the past three decades, rapid economic growth has improved living conditions considerably in many regions of China in a relatively short period of time. In rural China, both infant health and women's education levels have improved, as shown by a 36% decrease in the infant mortality rate between 1990 and 2000⁷ and a decrease in the illiteracy rate from 16% in 1990 to 7% in 2000.⁸ In China, the most developed region is the eastern coastal zone.⁹ Based on the China National Nutrition and Health Survey (NNAHS), the prevalence of combined overweight (weight-for-height z score >2–≤3) and obesity (weight-for-height z score >3) among children aged 0–6 years increased from 3.9% in 1992 to 5.4% in 2002, with a greater increase in girls than boys.¹⁰ However, the age-specific prevalence of overweight and obesity in urban and rural areas has not been reported.¹⁰ In a study of urban areas, Zong and Li reported that the prevalence of overweight and obesity in preschool children increased between 1986 and 2006.¹¹ Luo and Hu reported a substantial increase in overweight and obesity among children aged 2–6 years in urban areas but not in rural areas based on data from the China Health and Nutrition Survey (1989–1997).² Of note, the National Food and Nutrition Surveillance (NFANS) in China reported that ‘stunted obesity’ was emerging among rural children aged <5 years between 1990 and 1995.¹² These data showed that the prevalence of overweight increased from 1.1% in 1990 to 12.6% in 1995. Following improvement in the growth of children, the prevalence of overweight decreased to 3.8% in 1998 and 4.0% in 2005.¹²

Trends in the prevalence of overweight and obesity among rural preschool children in China have been reported by a few studies,2, 10, 12 but the findings were inconsistent. In regions in the midst of economic and nutritional transition, the increasing prevalence of overweight and obesity is accompanied by the existence of undernutrition.¹³ Income-adjusted risk ratios of overweight ranged from 1.7 to 7.8 for stunted vs non-stunted children aged 3–9 years in Russia, Brazil, the Republic of South Africa and China.¹⁴ However, the prevalence of overweight/obesity due to stunting among preschool children remains unclear, especially in rural China.

This study aimed to examine the trends in the prevalence of overweight and obesity, as well as the impact of stunting on overweight/obesity, among rural children aged <5 years from 1998 to 2005 using data from the population-based Child Health Care Surveillance System (CHCSS) in southeast China, a relatively developed region in China.