Bustos Patricia, Amigo Hugo, Muzzo Santiago, Ossa Ximena
Departamento de Nutrición, Facultad de Medicina, Universidad de Chile, Santiago de Chile.
Rev Med Chil. 2009 Oct;137(10):1301-8.
Improvements in environmental conditions may result in an earlier onset of thelarche. However, its onset is not homogeneous among different population groups.
To assess the relationship between nutritional status, ethnicity and age of thelarche.
Cross-sectional study of girls in second through sixth grade, attending 165 schools located in Chile's Araucania region. Of these, 231 girls who presented thelarche (breast button) were selected. The girls' surnames were used to identify their ethnicity: indigenous had three or four last names of Mapuche indigenous origin (n =113), while non-indigenous were those who only had Chilean-Spanish last names (n =118). Weight, height, waist circumference and skinfold thicknesses were measured and socio-economic background information was collected through a home interview.
The median age of thelarche was 10 years and 4 months, regardless of ethnic group. Multivariant models showed that an increase of one z score unit of body mass index (BMI) decreased the median age of thelarche by 5.6 months (CI: -7.24 to -3.90), controlling for the effect of different covariables. A decrease in one z score of height retards the median age of thelarche by 5.5 months (CI: 4.02 to 6.98). Ethnicity did not influence the age of thelarche.
The age of thelarche found by us is similar to that reported in international studies, it comes earlier as weight increases, is delayed as height decreases and is not related to ethnicity.
环境条件的改善可能会导致乳房发育提前开始。然而，不同人群中乳房发育开始的情况并不一致。
评估营养状况、种族与乳房发育年龄之间的关系。
对智利阿劳卡尼亚地区165所学校二至六年级女生进行横断面研究。从中选取了231名出现乳房发育（乳核）的女生。根据女生的姓氏来确定其种族：原住民有三个或四个源自马普切原住民的姓氏（n = 113），而非原住民则是只有智利 - 西班牙姓氏的女生（n = 118）。测量了体重、身高、腰围和皮褶厚度，并通过家访收集了社会经济背景信息。
无论种族如何，乳房发育的中位年龄为10岁零4个月。多变量模型显示，在控制不同协变量影响的情况下，体重指数（BMI）每增加一个z评分单位，乳房发育的中位年龄就会降低5.6个月（置信区间：-7.24至-3.90）。身高每降低一个z评分，乳房发育的中位年龄就会延迟5.5个月（置信区间：4.02至6.98）。种族并不影响乳房发育的年龄。
我们发现的乳房发育年龄与国际研究报告的相似，随着体重增加而提前，随着身高降低而延迟，且与种族无关。
