Background
Height and weight are important indicators in measuring children’s physical growth and development [
1]. They not only reflect nutrition and health condition in children, which is related to their socioeconomic status, but also influence their well-being and quality of later life [
2,
3]. Investigating the secular trend in physical growth for 0- to 7- year-old children reveals the patterns of child growth and thus, provides valuable biological evidence for policymakers to develop public health strategies [
2].
Since the 1950s, several studies have compared the secular growth trends between girls and boys in China’s urban and rural areas [
4,
5]. Over the past three decades, rapid economic development and enhanced living standards have enabled positive secular trends in children’s physical growth. Anthropometric measurements have become crucial for assessing socioeconomic status [
4]. However, the significant regional, east-west and socioeconomic disparities in China and their effect on children’s physical growth cannot be ignored [
6‐
8]. Under the economic reform in China, Guangzhou, as a pioneer of this economic opening, has been through rapid urbanization and economic development [
9,
10]. At the same time, income inequalities have emerged, along with an increase in health inequalities [
11]. Limited studies have tried to link inequalities of children’s growth to dramatic socioeconomic changes, which acts as important evidence for the government to develop policies that improve early childhood development and health care [
2,
12]. With the fast economic development in China, how inequalities in child growth development have changed over the past years in urban and rural areas of Guangzhou remains unclear, and further study is needed to estimate the magnitude of differences in urban and rural areas.
The present study investigated the influence of economic development in health inequalities. The goal of this study was to describe inequalities in child growth and its trend from 1985 to 2015 in Guangzhou. We focused on assessing 1) the difference in urban/rural child growth rate and its change over the past 30 years, 2) whether growth inequalities have disappeared under urbanization in Guangzhou, and 3) the association between economic development and growth inequality.
Discussion
In this study, we illustrated the secular trend in the physical development of children in urban and rural areas during 1985–2015 in Guangzhou. Results showed that the difference in height and weight decreased significantly from 1985 to 2015. In 2015, older children in rural areas weighted heavier than those of urban areas on average. Meanwhile, obesity kept increasing significantly in both areas, which seemed to be a more severe problem in rural areas. The prevalence of stunted growth decreased in both rural and urban areas. Economic development and urbanization were strongly associated with the prevalence of obesity and stunted growth.
As one of the largest cities in China, Guangzhou has underwent rapid urbanization, great improvement in economy and public health in the past three decades [
21,
22]. GDP per capita in Guangzhou has increased from about 784 USD in 1985 to 21,835 USD in 2015. There has been a positive trend in the physical growth of Chinese children with socioeconomic progress [
23]. In our study, we found that the physical growth of children in Guangzhou had increased significantly, and the inequality in their growth between urban and rural areas decreased in the past three decades. These results were consistent with previous studies [
24‐
26]. NSPGDC literature from national data, showed that between 1985 and 2005, those who lived in a coastal city such as Guangzhou was taller on average, than those living in inland and small-medium size cities [
27]. In the early stage of the study (1985–1995), the marked growth inequalities might result from poor economic status, lack of insurance and limited access to health services [
28,
29]. In the middle stage (1995–2005), substantial urban/rural inequalities remained, in parallel with a sustained upward trend in physical growth. The decreasing health inequalities were probably due to the rapid economic development and the Basic Health Insurance Scheme policy in China [
30,
31]. The gap between the physical growth of urban and rural children was further narrowed in the late stage (2005–2015). New health reforms, such as New Rural Co-operative Medical Care System (NRCMCS), were proposed during the same period. This basic public-health service project aimed to achieve health equity [
32,
33], especially for children of migrant workers who lived in the suburbs of Guangzhou [
34,
35]. In summary, economic development and expanding health care services largely decreased the urban/rural growth inequalities.
The differences in growth between urban and rural areas have narrowed over time. Generally, the physical growth status in children under 7 years old had been developed during the three decades both in rural and urban areas in Guangzhou. Besides, from the results of HAZ and WAZ in rural and urban areas and their differences in the three decades, we found that this gap of physical growth between rural and urban areas had become smaller since 2005. This changing pattern reflected that the physical growth rate of children in urban areas had decreased while increased in rural areas. These results were consistent with Xu’s cross-sectional surveys during 1985–2010, which reported that urban/rural differences in height were narrowed among children and adolescents aged 7–18 years in China [
2]. In the Netherlands, the world’s tallest population has come to a halt after 150 years of secular growth, which may have reached the optimal height distribution [
36]. Generally, economy affects children’s physical development by health care access, sanitary condition, nutrition and local infrastructure. Although income inequalities exist in urban and rural areas, adequate supply of nutrition, the improving economic and living conditions and better access to health care have gradually decreased the differences in growth rate of rural and urban children. Therefore, children in rural areas are catching up.
Another important nutritional issue was identified when physical growth of children was examined. The primary finding of our present study was that the prevalence of obesity in rural children increased 34-fold, which was more than that in urban children with better socioeconomic situations. Rapid urbanization in rural areas has led to new public health problems in children. It is widely reported that many changes in diet and physical activity are occurring simultaneously in the developing world and rural areas [
37]. These changes were followed by a dramatic increase in obesity, hypertension and cardiovascular disease [
38]. Urbanization and improving the economy in rural areas have enabled the rural population to purchase more processed foods and animal source foods [
39,
40]. Also, only a few people in rural areas received high education, and instead most of them lacked the knowledge of maintaining a healthy life style and preventive strategies for chronic diseases [
41‐
43]. A large proportion of the agricultural population and migrant population in the manufacturing industry lived in rural areas [
44]. Therefore, there might be fewer effective behavioral interventions to prevent obesity [
45].Our work highlighted an urgent need for developing appropriate interventions for children in the rural areas.
There were several strengths in our present study. Guangzhou represents an epitome of rapid urbanization and economic growth in China. Hence, it is important to examine the influence of its social changes over the past 30 years on child development. The results might predict the trends in other parts of China and even other developing countries that are going through dramatic social changes. In addition, the national surveillance data used in the present study was gathered throughout 30 successive years under strict quality control, and our study included a substantial proportion of the Chinese population in each period. However, several limitations existed in the present study. First, we lack the data of obesity and stunted growth from 1985 to 1995. We were not able to analyze or evaluate developmental indicators in depth in this period. Second, due to the limited number of data nodes in our survey, we were cautious in inferring the association between GDP, urbanization and growth, which might not be applicable for each individual. Furthermore, since the detailed demographic data of NSPGDC from 1985 to 2005 were not collected, we could not adjust for potentially important determinants of growth such as family income and parental education level in the present study. Therefore, how these determinants influence and to what extent they can explain the weight and height inequalities between urban and rural children remained unclear.
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