[Show abstract][Hide abstract] ABSTRACT: Declining age at menarche has been observed in many countries. In China, a decrease of 4.5 months per decade in the average age at menarche among the majority Han girls has recently been reported. However, the trends in age at menarche among ethnic minority girls over the past 25 years remain unknown.
To compare the differences in median age at menarche among girls aged 9-18 years across 24 ethnic minorities in 2010 and to estimate the trends in age at menarche in different ethnic minorities from 1985 to 2010.
We used data from six cross-sectional Chinese National Surveys on Students' Constitution and Health (1985, 1991, 1995, 2000, 2005, and 2010). The median age at menarche was estimated by using probit analysis.
In 2010, the ethnic minorities with the earliest age at menarche were the Koreans (11.79 years), Mongolians (12.44 years), and Zhuang (12.52 years). The three ethnic minorities with the latest age at menarche were the Sala (14.32 years), Yi (13.74 years), and Uighurs (13.67 years). From 1985 to 2010, the age at menarche declined in all 24 minority groups. The Lisu, Kazakh, and Korean minorities showed the largest reductions in age at menarche by 1.79 (p<0.05), 1.69 (p<0.05), and 1.57 (p<0.05) years, respectively, from 1985 to 2010. The Yi, Sala, and Li minorities showed the smallest reductions, with age at menarche declining by only 0.06 (p>0.05), 0.15 (p>0.05), and 0.15 (p>0.05) years, respectively, in the same period.
A large variation in age at menarche was observed among different ethnic minorities, with the earliest age at menarche found among Korean girls. A reduction in the average age at menarche appeared among most of the ethnic minorities over time, and the largest decrease was observed in Lisu, Kazakh, and Korean girls. Thus, health education should focus on targeting the specific needs of each ethnic minority group.
Full-text · Article · Jul 2015 · Global Health Action
[Show abstract][Hide abstract] ABSTRACT: Objectives:
To estimate the shifts in age at menarche from 1985 to 2010, compare the differences of average age at menarche between urban and rural groups, and determine the association of menarche with body mass index (BMI).
The data were obtained from 4 cross-sectional Chinese National Surveys on Students' Constitution and Health (1985, 1995, 2005, and 2010). In this representative sample of Chinese school-aged girls, the average age at menarche was determined using probit analysis and compared between urban and rural areas. Logistic regression was used to assess the association of BMI with the likelihood of having reached menarche.
The age at menarche in Chinese girls dropped from 13.41 years to 12.47 years from 1985 to 2010. There was a significant difference in age at menarche between urban and rural girls over time, with urban girls having their menarche earlier than rural girls. Logistic regression showed that a higher BMI was strongly associated with an increased likelihood of having reached menarche, even after controlling for age, urban or rural residence, province, social economic status, and school.
The analysis suggests a drop of about 4.5 months per decade in the average age at menarche over the past 25 years, and a significant inverse association between BMI and having reached menarche. Considering that both early menarche and higher BMI are significant risk factors for chronic diseases, and may act together in later years to the detriment of a woman's health, greater attention should be paid to the health of girls with earlier menarche and higher BMI.
Full-text · Article · Sep 2014 · Journal of Pediatrics
[Show abstract][Hide abstract] ABSTRACT: Objective:
To analyze the characteristics of sleep duration in Chinese primary and middle school students.
The data was collected from 30 provinces (Autonomous regions, Municipalities) in 165 363 Han Primary school students above 4 grade, the junior and senior high school students who participated in 2010 National Physical Fitness and Health Surveillance by using stratified random cluster sampling method, and the questionnaire of sleep duration, insufficient sleep and commuting way from school was conducted at the same time.χ² test and χ² linear-by-linear test were used to analyze the difference between the different groups, and logistic regression was used to analyze the factors of insufficient sleep.
Nationwide in 2010, 39.09% (64 646/165 363) of students reported they had more than 8 hours sleep duration per day, the prevalence was lower among urban (37.06% (30 767/83 027)) than rural (41.15% (33 879/82 336)) students (χ² = 290.53, P < 0.01), and higher among boys (40.25% (33 193/82 446)) than girls (37.94% (31 453/82 897)) (χ² = 92.51, P < 0.01). The prevalence of having more than 8 hours sleep duration per day in 9-12 years group, 13-15 years group and 16-18 years group was 70.24% (43 934/62 549), 31.31% (16 166/51 652) and 8.89% (546/51 162), respectively, and decreased with the age increasing (χ² linear-by-linear = 50 617.75, P < 0.01). The prevalence of insufficient sleep was 93.64% (154 838/165 363) in total students, the prevalence was higher among urban (94.94% (78 829/83 027)) than rural students (92.32% (76 009/82 336)) (χ² = 479.14, P < 0.01), and lower among boys (92.65% (76 408/82 466) than girls 94.61% (78 430/82 897) (χ² = 265.79, P < 0.01). The prevalence of insufficient sleep in 9-12 years group, 13-15 years group and 16-18 years group was 96.42% (60 310/62 549), 92.76% (47 912/51 562) and 91.11% (46 616/51 162), respectively. A multivariate logistic regression analysis (OR (95% CI)) revealed that the insufficient sleep was significantly associated with being urban (1.58 (1.51-1.65)), being girls (1.39 (1.34-1.45)), being 9-12 years group (2.77 (2.62-2.93)), living in the middle (1.19 (1.13-1.25)) or western (1.08 (1.03-1.13)) of China, and commuting from school by bicycle (1.21 (1.14-1.28)), bus/car (1.09 (1.03-1.15)), or in a boarding school (1.17 (1.10-1.24)).
The sleep duration in Chinese school children is low, a sizeable proportion of school children sleep less than the recommended hours. The prevalence of insufficient sleep is high, and there are significant differences in different groups.
Full-text · Article · Jul 2014 · Zhonghua yu fang yi xue za zhi [Chinese journal of preventive medicine]
[Show abstract][Hide abstract] ABSTRACT: Objective:
To identify gender differences among Chinese school-aged children from 1995 to 2010, and to project the future BMI-for-age Z-score distribution and prevalence of obesity.
The data were from four cross-sectional surveys (1995, 2000, 2005, and 2010) of Chinese National Surveys on Students Constitution and Health (CNSSCH) with a national representative sample of Chinese children, involving more than 200,000 participants at each survey. BMI-for-age Z-score distributional shifts overall and in percentiles were compared by gender. Average shift was calculated for four survey periods and used for projecting future distributions and obesity prevalence.
BMI-for-age Z-score increased more in their upper percentile distribution, indicating that Chinese children have become heavier over the past 15 years. Gender disparity in BMI-for-age Z-score has become wider during the period. Over a 15-year period, BMI-for-age Z-score shift among girls has been stable, while boy's BMI-for-age Z-score shifts has increased linearly. By 2020, the obesity prevalence is predicted to be 10.18% and 4.99% for boys and girls, respectively.
The wider gender disparity suggested a larger proportion of obesity in boys than in girls. Therefore, gender-specific preventive guidelines and public health policies for childhood obesity and cardiovascular diseases are urgently needed in China.
[Show abstract][Hide abstract] ABSTRACT: Children in China are experiencing a rapid increase in the prevalence of obesity, which is associated with hypertension. To compare the effect of body fat on blood pressure (BP) with that of the normal physical growth, we compared BP levels in Chinese children with different body fat levels. In the present population-based study, 13 972 children in the highest-skinfold-thickness-quartile group were individually matched to 13 972 children in the lowest-skinfold-thickness-quartile group by height and weight. Similarly, 5103 children in the highest-waist-circumference-quartile group were matched to the same number of children in the lowest-waist-circumference-quartile group. The high- and low-fat groups had similar height and weight but the high-fat group had significantly higher skinfold and waist circumference measurements. The differences in systolic BP (SBP) between the high- and low-skinfold-thickness groups were small: 0·01 (95 % CI - 0·41, 0·44) mmHg in boys and 0·20 (95 % CI - 0·15, 0·54) mmHg in girls. The differences in diastolic BP (DBP) were also small (0·39 and 0·38 mmHg for boys and girls, respectively) but were statistically significant. The differences in both SBP and DBP between the high- and low-waist-circumference groups were small but not statistically significant. For a given body size as measured by height and weight, relative body fat had little impact on BP levels in these children. Fat mass and lean mass may have a similar quantitative impact on BP in healthy-weight children.
Full-text · Article · Jan 2012 · The British journal of nutrition
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to quantify the relationships of height, weight and body mass index (BMI) with blood pressure (BP) levels in Chinese children and adolescents.
Height, weight, BMI and BP measurements were obtained from a nationally representative sample of 231,227 children aged 7-18 years. Body size measurements were converted to age- and sex-specific standard deviation (SD) scores. The relationships between body size and BP measurements were assessed using linear regression analysis.
All body size measurements were significantly associated with BP levels. Systolic BP increased 4.14, 3.70 and 2.88 mmHg in boys and 2.98, 2.63 and 1.87 mmHg in girls, corresponding to 1 SD increase in weight, BMI and height, respectively. A similar pattern was also observed for diastolic BP. After adjustment for height, systolic BP increased substantially with increasing weight (3.96 mmHg/SD increase for boys and 2.92 mmHg for girls). With adjustment for weight, systolic BP increased slightly with 1 SD increase in height (0.27 mmHg for boys and 0.10 mmHg for girls). The strength of the association between a body size measurement and BP varied among different ages, peaked at 10-11 years in girls and around 12-14 years in boys.
Weight is the most powerful driving force of BP in children and adolescents, followed by BMI and height. Height has little impact on BP in children with a given weight, while weight has considerable impact on BP in children with a given height.
No preview · Article · Nov 2011 · Journal of Paediatrics and Child Health
[Show abstract][Hide abstract] ABSTRACT: This For the determination of plant water content on-line, a sensor based on SWR (Standing-Wave Ratio) measurement principle was developed. To evaluate the feasibility of the proposed technique, a comparative experiment between the developed sensor (BD-II sensor) and SF-L (SF Type Sap Flow Systems, Germany) has been conducted over the past two years. The experimental results obtained from both instruments show a good agreement (R2=0.76). Therefore, the proposed technique is a promising tool in dynamically monitoring plant stem water.
[Show abstract][Hide abstract] ABSTRACT: To establish BMI percentile curves that describe the contemporary BMI distribution among Chinese children, and to compare their BMI percentile curves with those in two recently developed international references: the WHO and the US Centers for Disease Control and Prevention (US CDC) growth references.
A cross-sectional national survey.
Thirty provinces, municipalities and autonomous regions in China.
Nationally representative sample of 232 140 school students aged 7-18 years.
BMI percentile curves were established using the LMS method, and were compared with the percentiles of the WHO and the US CDC references. BMI distributions and growth patterns in Chinese children were dramatically different from those in the two international reference populations. Compared with the international reference populations, younger Chinese boys (7-12 years of age) had higher values of the percentiles above the median and lower values of the percentiles below the median, suggesting that they had larger proportions of extreme BMI values in both directions. Chinese girls and older Chinese boys (15-18 years of age) had substantially lower BMI percentiles than their counterparts in the reference populations, particularly those high percentiles among older age groups.
The present study described the unique patterns of BMI curves at the national level, and these curves are useful as a reference for comparing different regions and for monitoring changes over time in Chinese children. Higher proportions of children with extreme values in both directions indicate that China is currently facing both an increasing level of obesity and a high level of undernutrition, simultaneously.
Full-text · Article · Apr 2010 · Public Health Nutrition