Biro Frank M, Khoury Philip, Morrison John A
Division of Adolescent Medicine, Cincinnati Children's Hospital Medical Center, OH 45229-3039, USA.
Int J Androl. 2006 Feb;29(1):272-7; discussion 286-90. doi: 10.1111/j.1365-2605.2005.00602.x. Epub 2005 Dec 20.
Timing of normal pubertal maturation has received increased attention over the past several years. Age of menarche showed a dramatic decrease in the first half of the 20th century in Western nations; since 1960, the decrease in age of menarche has slowed and, in some societies, has actually increased. More recently, age of onset of pubertal maturation appears to have decreased, especially in girls. Multiple studies have demonstrated that childhood levels of obesity and ponderosity are associated with earlier menarche in girls. Earlier maturation in boys, however, is associated with lower adiposity and ponderosity. Secular changes in the United States as well as around the world have noted increases in prevalence as well as extent of overweight. Factors contributing to these changes include increases in calories and fast food consumption, decreases in physical activity, and increases in television viewing. There appear to have been selective advantages to lower metabolic rate (the 'thrifty' gene hypothesis), and earlier maturation. However, changes in caloric consumption, caloric density and physical activity, combined with greater lifespan, may allow expression of the adverse consequences of these adaptations, such as the metabolic syndrome or cancers.
在过去几年中，正常青春期发育的时间受到了越来越多的关注。20世纪上半叶，西方国家初潮年龄显著下降；自1960年以来，初潮年龄下降速度放缓，在一些社会中，初潮年龄实际上有所上升。最近，青春期发育开始的年龄似乎有所下降，尤其是在女孩中。多项研究表明，儿童期肥胖和超重水平与女孩初潮提前有关。然而，男孩早熟与较低的肥胖和超重程度有关。美国以及世界各地的长期变化表明超重的患病率和程度都有所增加。导致这些变化的因素包括热量摄入和快餐消费增加、体力活动减少以及看电视时间增加。较低的代谢率（“节俭”基因假说）和早熟似乎具有选择性优势。然而，热量消耗、热量密度和体力活动的变化，再加上寿命延长，可能会使这些适应性变化的不良后果显现出来，比如代谢综合征或癌症。
