社會經濟地位與學齡前兒童肥胖

背景與目的兒童是國家未來的主人翁，而早期肥胖則是最受關注的兒童健康議題之一。本研究包括三個子題，目的分別為：（1）瞭解學齡前兒童的生長發育及肥胖情形；（2）探討家庭社經地位對學齡前兒童肥胖及其BMI軌跡的影響及機制、（3）探討嬰兒期體重快速增加對學齡前兒童肥胖、BMI軌跡的影響及機制。方法本研究的資料來源為台灣出生世代研究計畫，該計畫採兩階段分層隨機抽樣方法，長期追蹤2005年出生的24,200名兒童，資料收集方法以家庭訪問為主，家訪時間為樣本出生後6個月、18個月、36個月，及5.5歲。首先，本研究參考美國疾病管制局出的方法，繪製台灣兒童成長曲線。接著，以潛在類別模型及潛在成長曲線模型分析兒童BMI軌跡，並以複羅吉斯迴歸、多元羅吉斯迴歸等方法，分析社會經濟地位對學齡前兒童肥胖、BMI軌跡的影響。最後，以路徑分析探討社會經濟地位是否透過父母親健康、兒童健康及行為，以及出生結果等中介變項，而影響兒童BMI的軌跡變化。結果子題一：採第85及95百分位的參考點，5.5歲的男生有9.6％為體重過重，5.3％為肥胖；5.5歲的女生有9.8％為體重過重，5.1％肥胖。子題二：學齡前兒童BMI軌跡可分為3類。第1類：BMI值先升後緩降（男生72.0％，女生75.4％）；第2類：BMI值先升後緩降，未超過20（男生23.4％，女生22.3％）；第3類：BMI值持續上升，且超過20（男生4.6％，女生2.4％）。整體而言，家庭社經地位愈高，學齡前兒童BMI成長的速度較低，且家庭社經地位會透過母親BMI、全母乳哺育時間長短而影響學齡前兒童BMI的起始狀態，以及透過兒童看電視時間長短，影響學齡前兒童BMI成長的速度。子題三：23.4％的男生及23.9％的女生，在嬰兒期有體重快速增加的現象。家庭社經地位會透過父親BMI及全母乳哺育時間影響兒童嬰兒期體重增加，以及各時間點兒童BMI的起始值。結論兒童肥胖已是公共衛生的問題。就影響肥胖的機制而言，家庭社會經濟地位會透過父母親健康行為、兒童健康行為等因素，影響兒童BMI成長的速度。因此，透過父母知識及能力的提升，可選擇及創造較健康的環境，進而減少學齡前兒童肥胖的情形。

關鍵字

學齡前兒童；肥胖；社會經濟地位

並列摘要

Backgrounds and objectives Children are our future; and early childhood obesity is one of the key issues in child health. This study consists of three aims: (1) to present the physical growth reference and obesity prevalence of preschool children; (2) to investigate the relationship and pathway between family socioeconomic status (SES) and children’s obesity and BMI trajectory; and (3) to examine the relationship and pathway between infancy rapid weight gain and obesity and BMI trajectory among preschool children. Methods Data came from the Taiwan Birth Cohort Study (TBCS). TBCS enrolled a nationally representative sample of 24,200 babies born in 2005, by using two-stage stratified random sampling. By 2012, four waves of face-to-face interview survey were conducted when children were at six months, 18 months, 36 months, and 5.5 years of age. We firstly used the USA CDC method to produce a growth reference between age zero to 5.5 years. Then we used latent class model and latent growth curve model to examine children’s BMI trajectory, and used multiple logistic regression and multi-nominal logistic regression to analyze pathways linking family SES to BMI trajectory. Finally, we used path analysis to investigate the mediating effect of parents’ health behavior, children’s health behavior, and birth outcomes on the relationship between SES and children’s BMI trajectory. Results Aim 1: The prevalence of overweight and obesity at 5.5 years of age were 9.6%, and 5.3% for boys, and 9.8%, and 5.1% for girls, respectively. Aim 2: Three distinct types of BMI trajectory were identified among TBCS children: Type 1－BMI leveled off after increasing, and then decreasing, Type 2－BMI BMI leveled off after increasing, and was less than 20, and Type 3－BMI increased, and was more than 20. The prevalence of Type 1, 2, 3 for boys was 72.0%, 23.4%, and 4.6%, and for girls was 75.4%, 22.3%, and 2.4%, respectively. Family SES was negatively associated with the velocity of BMI trajectory. In terms of pathway, family SES was associated with initial status of BMI trajectory, mediated by mother’s BMI and the breastfeeding duration. Moreover, the relationship of family SES and velocity of BMI trajectory was mediated by children’s TV-viewing. Aim 3: The prevalence of rapid weight gain during infancy was 23.4% and 23.9% for boys and girls, respectively. Infancy rapid weight gain was associated with initial status of BMI trajectory, which was mediated by family SES, father’s BMI, and breastfeeding duration. Conclusions Child obesity has been increasingly recognized as a public health problem. Our findings indicate that the relationship between family SES and BMI trajectory is mediated by parents’ and children’s health behaviors. As a result, promoting healthy lifestyle for children could be an important intervention to tackle the problem of child obesity.