In recent years, the prevalence of overweight and obesity has increasingly shifted toward younger ages, posing substantial risks to both the immediate and long-term health of children. In line with China's "Weight Management Year" initiative, the Macao SAR Government has incorporated obesity prevention into the Healthy Macao 2030 Blueprint, promoting a shift from passive treatment to proactive prevention. Therefore, developing a localized and scientifically sound BMI assessment tool for preschool children in Macao is of great significance.

To establish age- and sex-specific BMI percentile reference curves for preschool children in Macao, and to examine age and secular trends in thinness, overweight, and obesity, thereby providing evidence to support the improvement of growth and developmental health among Macao preschoolers.

Data were obtained from four rounds of Macao SAR Government physical fitness surveillance conducted in 2005, 2010, 2015, and 2020 with technical support from the China Institute of Sport Science. Preschool children were included, with sample sizes of 1 044, 1 065, 1 072, and 1 113 in the four respective years. Height and weight were collected and stratified by sex and age. BMI percentile curves were generated using the GAMLSS model to determine cut-offs for thinness, overweight, and obesity.

A total of 4 294 children [2 612 boys (60.8%) and 1 682 girls (39.2%); mean age (4.2±1.0) years; mean BMI (15.4±1.6) kg/m²] were included. Using the GAMLSS approach, we developed BMI percentile reference curves, a percentile-based scoring system, and cut-offs for thinness, normal weight, overweight, and obesity, forming a multidimensional BMI assessment framework integrating individualized precision evaluation, percentile scoring, and categorical classifications. The BMI curves declined and then rose with age, with nadirs at approximately 5 years for boys and 5.5 years for girls. Trend analyses showed slight increases in overweight and obesity rates from 2005 to 2020, but no statistically significant trends (P>0.05).

This study providing an individualized and accurate BMI evaluation tool for Macao preschool children, the BMI curves of Macao preschool children declined and then rose with age, with nadirs at approximately 5 years for boys and 5.5 years for girls. It is recommended that Macao increase opportunities for outdoor physical activity and sleep while reducing screen time to curb the early onset of childhood obesity.

近年来超重、肥胖呈低龄化趋势蔓延，严重影响着儿童当下及未来健康。在国家启动"体重管理年"活动之际，澳门特区政府《健康澳门蓝图》将肥胖防控纳入2030年目标，推动从"被动治病"转向"主动防病"，因此，制订澳门本土化学龄前儿童BMI科学评价工具具有重要意义。

建立澳门学龄前儿童BMI精准体质评估标准体系，并探究消瘦、超重和肥胖的年龄趋势和年代趋势，为提升澳门学龄前儿童生长发育水平提供参考。

数据来源于澳门特区政府体育局在2005、2010、2015、2020年在国家体育总局体育科学研究所技术支援下完成的市民体质监测，选取学龄前儿童为研究对象，4次体质监测儿童人数分别为1 044、1 065、1 072、1 113名。分性别、年龄收集纳入儿童的身高、体重数据，进而得出BMI。采用GAMLSS模型构建BMI百分位标准曲线，并划分消瘦、超重和肥胖临界值。

将澳门2005、2010、2015、2025年4次监测数据合并后学龄前儿童总人数为4 294名，其中男童2 612名（60.8%）、女童1 682名（39.2%），平均年龄为（4.2±1.0）岁，平均BMI为（15.4±1.6）kg/m²。采用GAMLSS模型得到澳门学龄前儿童BMI百分位标准曲线及参考值、百分制评分标准和消瘦、正常、超重和肥胖4个等级区间，构建了兼具个性化精准评估、百分制和等级制的BMI多维评估标准体系。BMI百分位标准曲线随年龄增长先降后升，且男、女童最低点分别在5岁和5.5岁。应用研究发现，2005—2020年澳门学龄前儿童超重率、肥胖率略有增加但无显著性趋势（P>0.05）。

本研究为澳门学龄前儿童提供了个性化的BMI精准评估工具，澳门学龄前儿童BMI百分位标准曲线随年龄增长先降后升，且男、女童最低点分别在5岁和5.5岁。建议创造条件增加学龄前儿童户外活动和睡眠时间，并减少屏幕暴露时间等，遏制肥胖低龄化趋势。