Malina R M, Peña Reyes M E, Tan Swee Kheng, Little B B
Tarleton State University, Stephenville, TX, USA.
Ann Hum Biol. 2004 Nov-Dec;31(6):634-46. doi: 10.1080/03014460400018085.
To evaluate secular change in the age at menarche between 1978 and 2000 in residents of a rural Zapotec-speaking community in Oaxaca, southern Mexico, using status quo and retrospective methods.
Status quo menarcheal status of girls 9-18 years of age in 1978 (n= 101) and 2000 (n=238) and retrospective ages at menarche of adult women 19+ years of age in 1978 (n = 228) and 2000 (n = 246) were obtained via interview. Probit analysis was used to estimate median ages at menarche and 95% confidence intervals (CI) for the status quo data. Analysis of variance and linear regression was used to compare the retrospective data across surveys.
The median ages at menarche of adolescents are 14.8+/-1.2 years (0.24 year, 95% CI 14.2-15.4 years) in 1978 and 13.0+/-1.0 years (0.10 year, 95% CI 12.7-13.3 years) in 2000. Age at menarche has declined by 1.8 years over about 23 years, 0.78 year/decade (95% CI = 0.65-0.91 year/decade). Recalled ages at menarche do not differ by age group in the 1978 survey, but differ significantly by age group in the 2000 survey (p <0.001). Within the 2000 survey, the two youngest age groups (< 29, 30-39 years) do not differ, but attain menarche earlier than women in the four older age groups (p < 0.05), who do not differ from each other in age at menarche. The estimated rates of secular decline in age at menarche in adult women vary between 0.38 and 0.42 years/decade (0.26-0.56 year/decade).
There is a major secular decline in the age at menarche of adolescent girls and young adult women between 1978 and 2000. The estimated rate of decline in adult women is about one-half of that in adolescent girls. The secular decline in age at menarche is consistent with corresponding secular gains height, sitting height and estimated leg length of children and adolescents in the community; corresponding secular gains are smaller in young adults 19-29 years.
采用现状法和回顾法，评估1978年至2000年间墨西哥南部瓦哈卡州一个说萨波特克语的农村社区居民月经初潮年龄的长期变化情况。
通过访谈获取了1978年（n = 101）和2000年（n = 238）9至18岁女孩的月经初潮现状，以及1978年（n = 228）和2000年（n = 246）19岁及以上成年女性的回顾性月经初潮年龄。采用概率分析估计现状数据的月经初潮中位数年龄和95%置信区间（CI）。方差分析和线性回归用于比较不同调查中的回顾性数据。
1978年青少年月经初潮的中位数年龄为14.8±1.2岁（0.24岁，95% CI 14.2 - 15.4岁），2000年为13.0±1.0岁（0.10岁，95% CI 12.7 - 13.3岁）。月经初潮年龄在约23年里下降了1.8岁，即0.78岁/十年（95% CI = 0.65 - 0.91岁/十年）。1978年调查中回忆的月经初潮年龄在各年龄组间无差异，但在2000年调查中各年龄组间差异显著（p < 0.001）。在2000年调查中，两个最年轻的年龄组（< 29岁，30 - 39岁）之间无差异，但月经初潮比四个年龄较大的年龄组的女性更早（p < 0.05），而这四个年龄较大的年龄组之间月经初潮年龄无差异。成年女性月经初潮年龄长期下降的估计速率在0.38至0.42岁/十年之间（0.26 - 0.56岁/十年）。
1978年至2000年间，青春期女孩和年轻成年女性的月经初潮年龄出现了显著的长期下降。成年女性的估计下降速率约为青春期女孩的一半。月经初潮年龄的长期下降与该社区儿童和青少年相应的身高、坐高和估计腿长的长期增长一致；19 - 29岁年轻成年人的相应长期增长较小。
