Saturday, June 03, 2006

China Menarche II

"Southern Chinese girls aged 11 years and 9 months to 12 years and 3
months in Hong Kong have a mean menarcheal age of 11.50 years
(standard deviation of 0.47) using the recollection method. Highly
significant differences are found when compared to the 12-year-old
girls in Hong Kong studied in the past decades. Therefore, a secular
trend of earlier menarcheal age is demonstrated.

So, LL, Yen, PK. Secular trend of menarcheal age in southern Chinese girls.
Z Morphol Anthropol. 1992 Jun;79(1):21-4.

Huen, KF, Leung, SS, Lau, JT, Cheung, AY, Leung, NK, Chiu, MC. Secular
trend in the sexual maturation of southern Chinese girls. Acta
Paediatr. 1997 Oct;86(10):1121-4.

"In 1993, a cross-sectional study of sexual maturation of normal
Chinese schoolgirls was performed in Hong Kong. The aim of the study
was to obtain an up-to-date reference for normal pubertal development
in Chinese girls. ... Menstrual status was recorded in 6467 girls over
6 y of age. ... The median age of menarche was 12.38 (95% CI
11.98-12.78) years. ... When comparison is made with similar studies
done in 1962 and 1979, a significant downward secular trend in sexual
maturation is observed (p < 0.01). Except for breast development the
downward secular trend in sexual maturation appears to be diminishing
and may be coming to a halt in the Chinese girls in Hong Kong. Their
median ages of sexual maturation are now among one of the earliest
medians recorded in the world population studied."

Growth status and menarche in urban and rural China
T. Hesketh, Qu Jian Ding, A. Tomkins


Objective: To examine the relationship between current age at menarche and growth status in an urban and rural area of Eastern China. Study design: Cross-sectional survey: self-completion questionnaire and anthropometry in 12 schools in urban Hangzhou and rural Chunan in Zhejiang Province. Results: The median menarcheal age calculated by probit analysis was significantly different in the two areas: 12.8 years (SD 0.9) in the urban area and 13.2 (SD 1.0) in the rural area (p < 0.001). Girls who reach menarche are significantly heavier and taller with higher BMIs than those of the same age who are pre-menarche. After adjustment for BMI and other possible confounders, urban girls were still menstruating significantly earlier than girls in rural areas (OR 3.3, 2.1-5.2). Conclusions: The age of menarche is probably still declining in China. Although BMI is an important factor in the onset of menstruation, some other unmeasured environmental variable may be implicated in this population.

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