Juul Anders, Magnusdottir Steinunn, Scheike Thomas, Prytz Sven, Skakkebaek Niels E
University Department of Growth and Reproduction, Rigshospitalet, Copenhagen, Denmark.
Int J Androl. 2007 Dec;30(6):537-42. doi: 10.1111/j.1365-2605.2007.00751.x. Epub 2007 Apr 24.
Voice break is a late, but characteristic event in male puberty. Assessment of age at voice break may be a relevant marker for epidemiological studies of male pubertal development. We investigated the timing of voice break and its association with explanatory variables [calendar year of admission in the boys choir and pre-pubertal body mass index (BMI)] by survival analysis techniques based on retrospective analyses of age at voice break in 463 Danish choir boys who were studied over a 10-year period. We found an overall median age at voice break of 14.0 [13.9-14.6] years, and a statistically significant downwards trend in age at voice break in the 10-year period (1994-2003) (log-rank test p = 0.0146). There was a statistically significant difference in age at voice break between boys in the different BMI quartiles in pre-puberty (p = 0.00822) with a tendency towards early voice break with increasing BMI standard deviation scores. Thus boys in the heaviest quartile at 8 years of age had an increased risk of early voice break (RR of 1.74 [1.14-2.65]) approximately 6 years later, compared with boys in the thinnest quartile. The earlier voice break seen during the 10-year observation period could however not exclusively be explained by a general increase in BMI in that period. Our findings indicate that puberty, as assessed by age at voice break in boys, may be starting earlier in Denmark as it has been observed in the USA, and suggest a relationship between pre-pubertal BMI and the timing of puberty.
变声是男性青春期后期出现的一个典型特征。变声年龄的评估可能是男性青春期发育流行病学研究的一个相关指标。我们通过生存分析技术，基于对463名丹麦唱诗班男孩变声年龄的回顾性分析，调查了变声时间及其与解释变量（唱诗班入学年份和青春期前体重指数）之间的关联，这些男孩在10年期间接受了研究。我们发现变声的总体中位年龄为14.0[13.9 - 14.6]岁，在10年期间（1994 - 2003年）变声年龄存在统计学上显著的下降趋势（对数秩检验p = 0.0146）。青春期前不同体重指数四分位数的男孩变声年龄存在统计学上的显著差异（p = 0.00822），随着体重指数标准差分数的增加，有变声提前的趋势。因此，8岁时处于最重四分位数的男孩在大约6年后变声提前的风险增加（相对风险为1.74[1.14 - 2.65]），而最瘦四分位数的男孩则不然。然而，在10年观察期内观察到的变声提前现象不能完全用该时期体重指数的普遍增加来解释。我们的研究结果表明，以男孩变声年龄评估的青春期在丹麦可能比在美国观察到的开始得更早，并提示青春期前体重指数与青春期时间之间存在关联。
