Cabrera Susanne M, Bright George M, Frane James W, Blethen Sandra L, Lee Peter A
J Pediatr Endocrinol Metab. 2014 Jan;27(1-2):47-51. doi: 10.1515/jpem-2013-0286.
A recent secular trend towards earlier thelarche has been suggested. The aim of this study is to examine normative ages of thelarche and menarche in contemporary US females.
Trained physicians documented Tanner breast stage by observation in a cross-sectional cohort. Age of menarche was self-reported. The subjects were healthy female children and adolescents. The mean age of thelarche was determined by probit analysis and the mean age of menarche was determined by using a normal time-to-event model.
Mean age of thelarche was 9.7 years among 610 females aged 3.0-17.9 years (70% non-Hispanic Caucasian (NHC), 14% African-Americans, 7% Hispanic, 9% "other"). The mean age of menarche was 12.8 years for NHC, with African-Americans having menarche 0.6 years earlier.
Thelarche occurred earlier than recently reported, while age of menarche remained unchanged, this supported a persistent secular trend towards earlier thelarche but stable age of menarche. This suggests that the observed thelarche is gonadotropin-independent or the tempo of pubertal advancement has slowed.
近期有研究表明乳房发育初潮出现有提前的长期趋势。本研究旨在调查当代美国女性乳房发育初潮和月经初潮的正常年龄。
经过培训的医生通过观察在一个横断面队列中记录坦纳乳房分期。月经初潮年龄由受试者自行报告。研究对象为健康的女童和青少年。乳房发育初潮的平均年龄通过概率分析确定，月经初潮的平均年龄通过使用正常事件时间模型确定。
在610名年龄在3.0至17.9岁的女性中（70%为非西班牙裔白人（NHC），14%为非裔美国人，7%为西班牙裔，9%为“其他”），乳房发育初潮的平均年龄为9.7岁。NHC的月经初潮平均年龄为12.8岁，非裔美国人的月经初潮时间提前0.6年。
乳房发育初潮比近期报道的时间更早，而月经初潮年龄保持不变，这支持了乳房发育初潮提前但月经初潮年龄稳定的持续长期趋势。这表明观察到的乳房发育初潮与促性腺激素无关，或者青春期发育进程的速度已经放缓。
